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Research involving Lowell Observatory staff 2023
(All publications)

This is a work ever in progress.

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*We are grateful for all the effort that went into making The SAO/NASA Astrophysics Data System (ADS) possible. The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A and can be found at: https://ui.adsabs.harvard.edu/

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Years: 2023 Bottom


  1. Upsdell, E., Giles, P., Romer, A., et al., 2023, MNRAS, 522, 5267, The XMM cluster survey: exploring scaling relations and completeness of the dark energy survey year 3 redMaPPer cluster catalogue
    We cross-match and compare characteristics of galaxy clusters identified in observations from two sky surveys using two completely different techniques. One sample is optically selected from the analysis of 3 years of Dark Energy Survey observations using the redMaPPer cluster detection algorithm. The second is X-ray selected from XMM observations analysed by the XMM Cluster Survey. The samples comprise a total area of 57.4 deg2, bounded by the area of four contiguous XMM survey regions that overlap the DES footprint. We find that the X-ray-selected sample is fully matched with entries in the redMaPPer catalogue, above > 20 and within 0.1 <$z$ <0.9. Conversely, only 38 per cent of the redMaPPer catalogue is matched to an X-ray extended source. Next, using 120 optically clusters and 184 X-ray-selected clusters, we investigate the form of the X-ray luminosity-temperature (LX -TX ), luminosity-richness (LX -), and temperature-richness (TX -) scaling relations. We find that the fitted forms of the LX -TX relations are consistent between the two selection methods and also with other studies in the literature. However, we find tentative evidence for a steepening of the slope of the relation for low richness systems in the X-ray-selected sample. When considering the scaling of richness with X-ray properties, we again find consistency in the relations (i.e. LX - and TX -) between the optical and X-ray-selected samples. This is contrary to previous similar works that find a significant increase in the scatter of the luminosity scaling relation for X-ray-selected samples compared to optically selected samples.
  2. Yu, Z., Martini, P., Penton, A., et al., 2023, MNRAS, 522, 4132, OzDES Reverberation Mapping Programme: Mg II lags and R-L relation
    The correlation between the broad line region radius and continuum luminosity (R-L relation) of active galactic nuclei (AGNs) is critical for single-epoch mass estimates of supermassive black holes (SMBHs). At z ~ 1-2, where AGN activity peaks, the R-L relation is constrained by the reverberation mapping (RM) lags of the Mg II line. We present 25 Mg II lags from the Australian Dark Energy Survey RM project based on 6 yr of monitoring. We define quantitative criteria to select good lag measurements and verify their reliability with simulations based on both the damped random walk stochastic model and the rescaled, resampled versions of the observed light curves of local, well-measured AGN. Our sample significantly increases the number of Mg II lags and extends the R-L relation to higher redshifts and luminosities. The relative iron line strength $\mathcal {R}_{\rm Fe}$ has little impact on the R-L relation. The best-fitting Mg IIR-L relation has a slope = 0.39 0.08 with an intrinsic scatter $\sigma _{\rm rl} = 0.15^{+0.03}_{-0.02}$ . The slope is consistent with previous measurements and shallower than the H R-L relation. The intrinsic scatter of the new R-L relation is substantially smaller than previous studies and comparable to the intrinsic scatter of the H R-L relation. Our new R-L relation will enable more precise single-epoch mass estimates and SMBH demographic studies at cosmic noon.
  3. Sidhu, S., Cloutis, E., Mann, P., et al., 2023, Icar, 398, 115522, Spectral and mineralogical effects of heating on CM chondrite and related asteroids
    Several carbonaceous chondrites (CCs) display evidence of aqueous and thermal alteration. However, the process of thermal alteration is not fully understood. To investigate the spectral variations caused by thermal alteration, we heated powders of CM2 CCs Murchison and Jbilet Winselwan, as well as a simulant Murchison mixture (WMM) and its end members. Heating was conducted up to 1200 C, in 100 C increments under a purified nitrogen environment. We also compared the findings of our study with results of previous heating experiments conducted on CCs to better understand the effect differing conditions have on the spectral properties observed. Formation of Fe3+ oxyhydroxides and the decomposition of serpentine due to heating are confirmed by both reflectance and X-ray diffraction (XRD) data. Fe3+ oxyhydroxides features such as a steep slope in between 350 to 700 nm, and an 850 nm feature can be seen starting at 300 and 400 C, respectively. The serpentine-associated features start to decompose at 700 C and disappear by 900 C. Spectra >1000 C are generally dark and featureless and above this temperature, mafic silicate absorption bands begin to appear. Our results show that heating-induced spectral variations are evident, and the nature of these changes depends on various parameters including temperature, experimental conditions, duration of heating, sample grain size, as well as mineralogical changes accompanying heating, and heterogeneity between CCs.
  4. Shipp, N., Panithanpaisal, N., Necib, L., et al., 2023, ApJ, 949, 44, Streams on FIRE: Populations of Detectable Stellar Streams in the Milky Way and FIRE
    We present the first detailed comparison of populations of dwarf galaxy stellar streams in cosmological simulations and the Milky Way. In particular, we compare streams identified around 13 Milky Way analogs in the FIRE-2 simulations to streams observed by the Southern Stellar Stream Spectroscopic Survey (S 5). For an accurate comparison, we produce mock Dark Energy Survey (DES) observations of the FIRE streams and estimate the detectability of their tidal tails and progenitors. The number and stellar mass distributions of detectable stellar streams is consistent between observations and simulations. However, there are discrepancies in the distributions of pericenters and apocenters, with the detectable FIRE streams, on average, forming at larger pericenters (out to >110 kpc) and surviving only at larger apocenters (40 kpc) than those observed in the Milky Way. We find that the population of high-stellar-mass dwarf galaxy streams in the Milky Way is incomplete. Interestingly, a large fraction of the FIRE streams would only be detected as intact satellites in DES-like observations, since their tidal tails have too low surface brightness to be detectable. We thus predict a population of yet-undetected tidal tails around Milky Way satellites, as well as a population of fully undetected low-surface-brightness stellar streams, and estimate their detectability with the Rubin Observatory. Finally, we discuss the causes and implications of the discrepancies between the stream populations in FIRE and the Milky Way, and explore future avenues for tests of satellite disruption in cosmological simulations.
  5. Schwamb, M., Jones, R., Yoachim, P., et al., 2023, ApJS, 266, 22, Tuning the Legacy Survey of Space and Time (LSST) Observing Strategy for Solar System Science
    The Vera C. Rubin Observatory is expected to start the Legacy Survey of Space and Time (LSST) in early to mid-2025. This multiband wide-field synoptic survey will transform our view of the solar system, with the discovery and monitoring of over five million small bodies. The final survey strategy chosen for LSST has direct implications on the discoverability and characterization of solar system minor planets and passing interstellar objects. Creating an inventory of the solar system is one of the four main LSST science drivers. The LSST observing cadence is a complex optimization problem that must balance the priorities and needs of all the key LSST science areas. To design the best LSST survey strategy, a series of operation simulations using the Rubin Observatory scheduler have been generated to explore the various options for tuning observing parameters and prioritizations. We explore the impact of the various simulated LSST observing strategies on studying the solar system's small body reservoirs. We examine what are the best observing scenarios and review what are the important considerations for maximizing LSST solar system science. In general, most of the LSST cadence simulations produce 5% or less variations in our chosen key metrics, but a subset of the simulations significantly hinder science returns with much larger losses in the discovery and light-curve metrics.
  6. Lee, J., Acevedo, M., Sako, M., et al., 2023, AJ, 165, 222, The Dark Energy Survey Supernova Program: Corrections on Photometry Due to Wavelength-dependent Atmospheric Effects
    Wavelength-dependent atmospheric effects impact photometric supernova flux measurements for ground-based observations. We present corrections on supernova flux measurements from the Dark Energy Survey Supernova Program's 5YR sample (DES-SN5YR) for differential chromatic refraction (DCR) and wavelength-dependent seeing, and we show their impact on the cosmological parameters w and m . We use g - i colors of Type Ia supernovae to quantify astrometric offsets caused by DCR and simulate point-spread functions (PSFs) using the GalSIM package to predict the shapes of the PSFs with DCR and wavelength-dependent seeing. We calculate the magnitude corrections and apply them to the magnitudes computed by the DES-SN5YR photometric pipeline. We find that for the DES-SN5YR analysis, not accounting for the astrometric offsets and changes in the PSF shape cause an average bias of +0.2 mmag and -0.3 mmag, respectively, with standard deviations of 0.7 mmag and 2.7 mmag across all DES observing bands (griz) throughout all redshifts. When the DCR and seeing effects are not accounted for, we find that w and m are lower by less than 0.004 0.02 and 0.001 0.01, respectively, with 0.02 and 0.01 being the 1 statistical uncertainties. Although we find that these biases do not limit the constraints of the DES-SN5YR sample, future surveys with much higher statistics, lower systematics, and especially those that observe in the u band will require these corrections as wavelength-dependent atmospheric effects are larger at shorter wavelengths. We also discuss limitations of our method and how they can be better accounted for in future surveys.
  7. Sanchez, J., Omori, Y., Chang, C., et al., 2023, MNRAS, 522, 3163, Mapping gas around massive galaxies: cross-correlation of DES Y3 galaxies and Compton-y maps from SPT and Planck
    We cross-correlate positions of galaxies measured in data from the first three years of the Dark Energy Survey with Compton-y maps generated using data from the South Pole Telescope (SPT) and the Planck mission. We model this cross-correlation measurement together with the galaxy autocorrelation to constrain the distribution of gas in the Universe. We measure the hydrostatic mass bias or, equivalently, the mean halo bias-weighted electron pressure <bhPe >, using large-scale information. We find <bhPe > to be $[0.16^{+0.03}_{-0.04},0.28^{+0.04}_{-0.05},0.45^{+0.06}_{-0.10},0.54^{+0.08}_{-0.07},0.61^{+0.08}_{-0.06},0.63^{+0.07}_{-0.08}]$ meV cm-3 at redshifts z ~ [0.30, 0.46, 0.62, 0.77, 0.89, 0.97]. These values are consistent with previous work where measurements exist in the redshift range. We also constrain the mean gas profile using small-scale information, enabled by the high-resolution of the SPT data. We compare our measurements to different parametrized profiles based on the cosmo-OWLS hydrodynamical simulations. We find that our data are consistent with the simulation that assumes an AGN heating temperature of 108.5 K but are incompatible with the model that assumes an AGN heating temperature of 108.0 K. These comparisons indicate that the data prefer a higher value of electron pressure than the simulations within r500c of the galaxies' haloes.
  8. dal Ponte, M., Santiago, B., Carnero Rosell, A., et al., 2023, MNRAS, 522, 1951, Ultracool dwarfs candidates based on 6 yr of the Dark Energy Survey data
    We present a sample of 19 583 ultracool dwarf candidates brighter than z 23 selected from the Dark Energy Survey DR2 coadd data matched to VHS DR6, VIKING DR5, and AllWISE covering ~ 480 deg2. The ultracool candidates were first pre-selected based on their (i-z), (z-Y), and (Y-J) colours. They were further classified using a method that compares their optical, near-infrared, and mid-infrared colours against templates of M, L, and T dwarfs. 14 099 objects are presented as new L and T candidates and the remaining objects are from the literature, including 5342 candidates from our previous work. Using this new and deeper sample of ultracool dwarf candidates we also present: 20 new candidate members to nearby young moving groups and associations, variable candidate sources and four new wide binary systems composed of two ultracool dwarfs. Finally, we also show the spectra of 12 new ultracool dwarfs discovered by our group and presented here for the first time. These spectroscopically confirmed objects are a sanity check of our selection of ultracool dwarfs and photometric classification method.
  9. Oszkiewicz, D., Troianskyi, V., Galad, A., et al., 2023, Icar, 397, 115520, Spins and shapes of basaltic asteroids and the missing mantle problem
    Basaltic V-type asteroids are common in the inner part of the Main Asteroid Belt and much less abundant in the mid and outer parts. They are of scientific interest because they sample crusts and mantles of theoretically plentiful differentiated planetesimals that existed in the Solar System four billion years ago. Some Solar System theories suggest that those objects formed in the terrestrial planet region and were then implanted in the main asteroid belt. In consequence, we should observe a large number of fragments of multiple differentiated planetesimals in the inner Main Belt. That region of the Asteroid Belt is filled with V-type fragments; however, they are difficult to tell apart from typical Vestoids and Vesta fugitives. In this work, we focus on physical and dynamical characterization of V-types in the inner Main-Belt and aim to reconcile those properties with the planetesimal formation and evolution theories.

    We conducted an observing campaign over the years 2013-2022 and obtained photometric observations of V-type asteroids located mostly outside the Vesta family at specific locations of the inner Main Belt (the so-called Cells I and II). The total number of partial dense photometric lightcurves obtained in this study was 2910. We were able to model 100 V-types. We further supplement those data with 133 spins of V-types from the DAMIT database and 237 objects derived from Gaia DR3 (Durech & Hanus 2023). We found 78% 11% and 38% 13% retrograde rotators in Cell I and II, respectively. This statistic is remarkably consistent with the numerical simulations of the escape paths of Vesta fugitives that predict 81% retrograde rotators in Cell I and 40% in Cell II after the dynamical integration of 2 Gys. Based on our statistics we conclude that if there are non-Vestoids in the inner main belt, they are likely to be very few. This is consistent with the small fraction of anomalous HED meteorites in meteorite collections, small number of non-Vestoids in the middle and outer Main Belt and points to planetesimal formation location close to the Sun.

  10. Duck, A., Martin, D., Gill, S., et al., 2023, MNRAS, 521, 6305, The EBLM project X. Benchmark masses, radii, and temperatures for two fully convective M-dwarfs using K2
    M-dwarfs are the most abundant stars in the galaxy and popular targets for exoplanet searches. However, their intrinsic faintness and complex spectra inhibit precise characterization. We only know of dozens of M-dwarfs with fundamental parameters of mass, radius, and effective temperature characterized to better than a few per cent. Eclipsing binaries remain the most robust means of stellar characterization. Here we present two targets from the Eclipsing Binary Low Mass (EBLM) survey that were observed with K2: EBLM J0055-00 and EBLM J2217-04. Combined with HARPS and CORALIE spectroscopy, we measure M-dwarf masses with precisions better than 5 per cent, radii better than 3 per cent, and effective temperatures on order 1 per cent. However, our fits require invoking a model to derive parameters for the primary star and fitting the M-dwarf using the transit and radial velocity observations. By investigating three popular stellar models, we determine that the model uncertainty in the primary star is of similar magnitude to the statistical uncertainty in the model fits of the secondary M-dwarf. Therefore, whilst these can be considered benchmark M-dwarfs, we caution the community to consider model uncertainty when pushing the limits of precise stellar characterization.
  11. Koposov, S., Erkal, D., Li, T., et al., 2023, MNRAS, 521, 4936, S 5: Probing the Milky Way and Magellanic Clouds potentials with the 6D map of the Orphan-Chenab stream
    We present a 6D map of the Orphan-Chenab (OC) stream by combining the data from Southern Stellar Stream Spectroscopic Survey (S5) and Gaia. We reconstruct the proper motion, radial velocity, distance, on-sky track, and stellar density along the stream with spline models. The stream has a total luminosity of MV = -8.2 and metallicity of [Fe/H] = -1.9, similar to classical Milky Way (MW) satellites like Draco. The stream shows drastic changes in its physical width varying from 200 pc to 1 kpc, but a constant line-of-sight velocity dispersion of 5 $\mathrm{km\, s^{-1}}$. Despite the large apparent variation in the stellar number density along the stream, the flow rate of stars along the stream is remarkably constant. We model the 6D stream track by a Lagrange-point stripping method with a flexible MW potential in the presence of a moving extended Large Magellanic Cloud (LMC). This allows us to constrain the mass profile of the MW within the distance range 15.6 < r < 55.5 kpc, with the best measured enclosed mass of $(2.85\pm 0.1)\times 10^{11}\, \mathrm{\, M_\odot }$ within 32.4 kpc. Our stream measurements are highly sensitive to the LMC mass profile with the most precise measurement of its enclosed mass made at 32.8 kpc, $(7.02\pm 0.9)\times 10^{10}\, {\rm M}_\odot$. We also detect that the LMC dark matter halo extends to at least 53 kpc. The fitting of the OC stream allows us to constrain the past LMC trajectory and the degree of dynamical friction it experienced. We demonstrate that the stars in the OC stream show large energy and angular momentum spreads caused by LMC perturbation.
  12. Windsor, J., Robinson, T., Kopparapu, R., et al., 2023, PSJ, 4, 94, A Radiative-convective Model for Terrestrial Planets with Self-consistent Patchy Clouds
    Clouds are ubiquitous: they arise for every solar system planet that possesses an atmosphere and have also been suggested as a leading mechanism for obscuring spectral features in exoplanet observations. As exoplanet observations continue to improve, there is a need for efficient and general planetary climate models that appropriately handle the possible cloudy atmospheric environments that arise on these worlds. We generate a new 1D radiative-convective terrestrial planet climate model that self-consistently handles patchy clouds through a parameterized microphysical treatment of condensation and sedimentation processes. Our model is general enough to recreate Earth's atmospheric radiative environment without overparameterization, while also maintaining a simple implementation that is applicable to a wide range of atmospheric compositions and physical planetary properties. We first validate this new 1D patchy-cloud radiative-convective climate model by comparing it to Earth thermal structure data and to existing climate and radiative-transfer tools. We produce partially clouded Earth-like climates with cloud structures that are representative of deep tropospheric convection and are adequate 1D representations of clouds within rocky planet atmospheres. After validation against Earth, we then use our partially clouded climate model and explore the potential climates of super-Earth exoplanets with secondary nitrogen-dominated atmospheres which we assume are abiotic. We also couple the partially clouded climate model to a full-physics, line-by-line radiative-transfer model and generate high-resolution spectra of simulated climates. These self-consistent climate-to-spectral models bridge the gap between climate modeling efforts and observational studies of rocky worlds.
  13. Chandler, C., Oldroyd, W., Hsieh, H., et al., 2023, RNAAS, 7, 102, New Active Asteroid (588045) 2007 FZ18
    We present evidence that, on UT 2018 February 15, main-belt asteroid (588045) 2007 FZ18 displayed cometary activity in the form of two tails, one each in the anti-solar and anti-motion directions. Activity was first identified by volunteers of the NASA Partner program Active Asteroids, a Citizen Science program hosted on the Zooniverse platform, in an image acquired with the Dark Energy Camera on the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory in Chile. Notably, (588045) 2007 FZ18 is inbound toward perihelion, so telescope observations are timely to detect a possible second activity outburst.
  14. Long, J., Males, J., Haffert, S., et al., 2023, AJ, 165, 216, Improved Companion Mass Limits for Sirius A with Thermal Infrared Coronagraphy Using a Vector-apodizing Phase Plate and Time-domain Starlight-subtraction Techniques
    We use observations with the infrared-optimized Magellan Adaptive Optics (MagAO) system and Clio camera in 3.9 m light to place stringent mass constraints on possible undetected companions to Sirius A. We suppress the light from Sirius A by imaging it through a grating vector-apodizing phase plate coronagraph with a 180 dark region (gvAPP-180). To remove residual starlight in postprocessing, we apply a time-domain principal-components-analysis-based algorithm we call PCA-Temporal, which uses eigen time series rather than eigenimages to subtract starlight. By casting the problem in terms of eigen time series, we reduce the computational cost of postprocessing the data, enabling the use of the fully sampled data set for improved contrast at small separations. We also discuss the impact of retaining fine temporal sampling of the data on final contrast limits. We achieve postprocessed contrast limits of 1.5 10-6-9.8 10-6 outside of 0.75, which correspond to planet masses of 2.6-8.0 M J. These are combined with values from the recent literature of high-contrast imaging observations of Sirius to synthesize an overall completeness fraction as a function of mass and separation. After synthesizing these recent studies and our results, the final completeness analysis rules out 99% of 9 M J planets from 2.5 to 7 au.
  15. Koehn, B., Shelus, P., Ries, J., et al., 2023, MPEC, 2023-J103, Comet P/2022 m1 = P/2000 OZ21 Loneos-Panstarrs
  16. Kareta, T., Noonan, J., Harris, W., et al., 2023, PSJ, 4, 85, Ice, Ice, Maybe? Investigating 46P/Wirtanen's Inner Coma for Icy Grains
    The release of volatiles from comets is usually from direct sublimation of ices on the nucleus, but for very or hyperactive comets other sources have to be considered to account for the total production rates. In this work, we present new near-IR (NIR) imaging and spectroscopic observations of 46P/Wirtanen taken during its close approach to Earth on 2018 December 19 with the MMIRS instrument at the MMT Observatory to search for signatures of icy or ice-rich grains in its inner coma that might explain its previously reported excess water production. The morphology of the images does not suggest any change in grain properties within the field of view, and the NIR spectra do not show the characteristic absorption features of water ice. Using a new Markov Chain Monte Carlo-based implementation of the spectral modeling approach of Protopapa et al., we estimate the areal water ice fraction of the coma to be <0.6%. When combined with slit-corrected Af values for the J, H, and K bands and previously measured dust velocities for this comet, we estimate an icy grain production rate of less than 4.6 kg s-1. This places a strict constraint on the water production rate from pure icy grains in the coma, and in turn we find that for the 2018-2019 apparition approximately 64% of 46P's surface was actively sublimating water near perihelion. We then discuss 46P's modern properties within the context of other (formerly) hyperactive comets to understand how these complex objects evolve.
  17. Graham, K., O'Donnell, J., Silverstein, M., et al., 2023, RNAAS, 7, 86, Cool Cores in Clusters of Galaxies in the Dark Energy Survey
    We search for the presence of cool cores in optically selected galaxy clusters from the Dark Energy Survey (DES) and investigate their prevalence as a function of redshift and cluster richness. Clusters were selected from the redMaPPer analysis of three years of DES observations that have archival Chandra X-ray observations, giving a sample of 99 clusters with a redshift range of 0.11 < z < 0.87 and a richness range of 25 < < 207. Using the X-ray data, the core temperature was compared to the outer temperature to identify clusters where the core temperature is a factor of 0.7 or less than the outer temperature. We found a cool core fraction of approximately 20% with no significant trend in the cool core fraction with either redshift or richness.
  18. French, R., McGhee-French, C., Gordon, M., et al., 2023, Icar, 395, 115474, Uranus ring occultation observations: 1977-2006
    The Uranian rings were discovered serendipitously on 10 March 1977 during a stellar occultation (Elliot et al., 1977a; Millis et al., 1977), and a rich set of subsequent Earth-based occultations revealed that these narrow and sharp-edged rings were eccentric and inclined, precessing under the gravitational influence of the oblate central planet. Considerable progress has been made in understanding the observed characteristics of narrow rings and sharp edges (Nicholson et al., 2018) and their associated dynamics (Longaretti, 2018), but ever since their discovery, the Uranian rings have posed dynamical puzzles that resist simple explanations. The observational basis to address these questions for the Uranus system rests largely on occultation measurements of the narrow rings spanning nearly 30 years, beginning in 1977 and concluding most recently in 2006. Nearly all of these occultation data sets are available in digital form on NASA's Planetary Data System (PDS) Ring-Moon Systems node, but many of them have not been previously published or described in detail. This paper serves as a guide to the PDS archive and provides essential information about the observations and the methods used to determine the ring widths, mean optical depths, and occultation event times from individual occultation profiles. Additional detail is provided in the Supplementary Online Material accompanying this publication. In a companion paper (French et al., 2023b), we make use of these observations to determine the Uranus ring orbits, pole direction, and gravity field, and the orbital characteristics and masses of three small Uranian moons - Cressida, Ophelia, and Cordelia - from their forced normal modes on the rings.
  19. Lemos, P., Weaverdyck, N., Rollins, R., et al., 2023, MNRAS, 521, 1184, Robust sampling for weak lensing and clustering analyses with the Dark Energy Survey
    Recent cosmological analyses rely on the ability to accurately sample from high-dimensional posterior distributions. A variety of algorithms have been applied in the field, but justification of the particular sampler choice and settings is often lacking. Here, we investigate three such samplers to motivate and validate the algorithm and settings used for the Dark Energy Survey (DES) analyses of the first 3 yr (Y3) of data from combined measurements of weak lensing and galaxy clustering. We employ the full DES Year 1 likelihood alongside a much faster approximate likelihood, which enables us to assess the outcomes from each sampler choice and demonstrate the robustness of our full results. We find that the ellipsoidal nested sampling algorithm MULTINEST reports inconsistent estimates of the Bayesian evidence and somewhat narrower parameter credible intervals than the sliced nested sampling implemented in POLYCHORD. We compare the findings from MULTINEST and POLYCHORD with parameter inference from the Metropolis-Hastings algorithm, finding good agreement. We determine that POLYCHORD provides a good balance of speed and robustness for posterior and evidence estimation, and recommend different settings for testing purposes and final chains for analyses with DES Y3 data. Our methodology can readily be reproduced to obtain suitable sampler settings for future surveys.
  20. Golden-Marx, J., Zhang, Y., Ogando, R., et al., 2023, MNRAS, 521, 478, Characterizing the intracluster light over the redshift range 0.2 < z < 0.8 in the DES-ACT overlap
    We characterize the properties and evolution of bright central galaxies (BCGs) and the surrounding intracluster light (ICL) in galaxy clusters identified in the Dark Energy Survey and Atacama Cosmology Telescope Survey (DES-ACT) overlapping regions, covering the redshift range 0.20 < z < 0.80. Over this redshift range, we measure no change in the ICL's stellar content (between 50 and 300 kpc) in clusters with log10(M200m,SZ/M) >14.4. We also measure the stellar mass-halo mass (SMHM) relation for the BCG+ICL system and find that the slope, , which characterizes the dependence of M200m,SZ on the BCG+ICL stellar mass, increases with radius. The outskirts are more strongly correlated with the halo than the core, which supports that the BCG+ICL system follows a two-phase growth, where recent growth (z < 2) occurs beyond the BCG's core. Additionally, we compare our observed SMHM relation results to the IllustrisTNG300-1 cosmological hydrodynamic simulations and find moderate qualitative agreement in the amount of diffuse light. However, the SMHM relation's slope is steeper in TNG300-1 and the intrinsic scatter is lower, likely from the absence of projection effects in TNG300-1. Additionally, we find that the ICL exhibits a colour gradient such that the outskirts are bluer than the core. Moreover, for the lower halo mass clusters (log10(M200m,SZ/M) < 14.59), we detect a modest change in the colour gradient's slope with lookback time, which combined with the absence of stellar mass growth may suggest that lower mass clusters have been involved in growth via tidal stripping more recently than their higher mass counterparts.
  21. Stone, Z., Shen, Y., Burke, C., et al., 2023, MNRAS, 521, 836, Correction to: Optical variability of quasars with 20-year photometric light curves
  22. Daly, R., Ernst, C., Barnouin, O., et al., 2023, Natur, 616, 443, Successful kinetic impact into an asteroid for planetary defence
    Although no known asteroid poses a threat to Earth for at least the next century, the catalogue of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation1,2. Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid1-3. A test of kinetic impact technology was identified as the highest-priority space mission related to asteroid mitigation1. NASA's Double Asteroid Redirection Test (DART) mission is a full-scale test of kinetic impact technology. The mission's target asteroid was Dimorphos, the secondary member of the S-type binary near-Earth asteroid (65803) Didymos. This binary asteroid system was chosen to enable ground-based telescopes to quantify the asteroid deflection caused by the impact of the DART spacecraft4. Although past missions have utilized impactors to investigate the properties of small bodies5,6, those earlier missions were not intended to deflect their targets and did not achieve measurable deflections. Here we report the DART spacecraft's autonomous kinetic impact into Dimorphos and reconstruct the impact event, including the timeline leading to impact, the location and nature of the DART impact site, and the size and shape of Dimorphos. The successful impact of the DART spacecraft with Dimorphos and the resulting change in the orbit of Dimorphos7 demonstrates that kinetic impactor technology is a viable technique to potentially defend Earth if necessary.
  23. Thomas, C., Naidu, S., Scheirich, P., et al., 2023, Natur, 616, 448, Orbital period change of Dimorphos due to the DART kinetic impact
    The Double Asteroid Redirection Test (DART) spacecraft successfully performed the first test of a kinetic impactor for asteroid deflection by impacting Dimorphos, the secondary of near-Earth binary asteroid (65803) Didymos, and changing the orbital period of Dimorphos. A change in orbital period of approximately 7 min was expected if the incident momentum from the DART spacecraft was directly transferred to the asteroid target in a perfectly inelastic collision1, but studies of the probable impact conditions and asteroid properties indicated that a considerable momentum enhancement () was possible2,3. In the years before impact, we used lightcurve observations to accurately determine the pre-impact orbit parameters of Dimorphos with respect to Didymos4-6. Here we report the change in the orbital period of Dimorphos as a result of the DART kinetic impact to be 33.0 1.0 (3) min. Using new Earth-based lightcurve and radar observations, two independent approaches determined identical values for the change in the orbital period. This large orbit period change suggests that ejecta contributed a substantial amount of momentum to the asteroid beyond what the DART spacecraft carried.
  24. Li, J., Hirabayashi, M., Farnham, T., et al., 2023, Natur, 616, 452, Ejecta from the DART-produced active asteroid Dimorphos
    Some active asteroids have been proposed to be formed as a result of impact events1. Because active asteroids are generally discovered by chance only after their tails have fully formed, the process of how impact ejecta evolve into a tail has, to our knowledge, not been directly observed. The Double Asteroid Redirection Test (DART) mission of NASA2, in addition to having successfully changed the orbital period of Dimorphos3, demonstrated the activation process of an asteroid resulting from an impact under precisely known conditions. Here we report the observations of the DART impact ejecta with the Hubble Space Telescope from impact time T + 15 min to T + 18.5 days at spatial resolutions of around 2.1 km per pixel. Our observations reveal the complex evolution of the ejecta, which are first dominated by the gravitational interaction between the Didymos binary system and the ejected dust and subsequently by solar radiation pressure. The lowest-speed ejecta dispersed through a sustained tail that had a consistent morphology with previously observed asteroid tails thought to be produced by an impact4,5. The evolution of the ejecta after the controlled impact experiment of DART thus provides a framework for understanding the fundamental mechanisms that act on asteroids disrupted by a natural impact1,6.
  25. Massey, P., Neugent, K., Morrell, N., 2023, ApJ, 947, 77, Constraints on the Binarity of the WN3/O3 Class of Wolf-Rayet Stars
    The WN3/O3 Wolf-Rayet (WR) stars were discovered as part of our survey for WRs in the Magellanic Clouds. The WN3/O3s show the emission lines of a high-excitation WN star and the absorption lines of a hot O-type star, but our prior work has shown that the absorption spectrum is intrinsic to the WR star. Their place in the evolution of massive stars remains unclear. Here we investigate the possibility that they are the products of binary evolution. Although these are not WN3+O3 V binaries, they could still harbor unseen companions. To address this possibility, we have conducted a multiyear radial velocity study of six of the nine known WN3/O3s. Our study finds no evidence of statistically significant radial velocity variations, and allows us to set stringent upper limits on the mass of any hypothetical companion star: for probable orbital inclinations, any companion with a period less than 100 days must have a mass <2M . For periods less than 10 days, any companion would have to have a mass <1M . We argue that scenarios where any such companion is a compact object are unlikely. The absorption lines indicate a normal projected rotational velocity, making it unlikely that these stars evolved with the aid of a companion star that has since merged. The modest rotation also suggests that these stars are not the result of homogenous evolution. Thus it is likely that these stars are a normal but short-lived stage in the evolution of massive stars. * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.
  26. Yu, Z., Martini, P., Penton, A., et al., 2023, MNRAS, OzDES Reverberation Mapping Program: Mg II Lags and R-L relation
    The correlation between the broad line region radius and continuum luminosity (R - L relation) of active galactic nuclei (AGN) is critical for single-epoch mass estimates of supermassive black holes (SMBHs). At z ~ 1 - 2, where AGN activity peaks, the R - L relation is constrained by the reverberation mapping (RM) lags of the Mg II line. We present 25 Mg II lags from the Australian Dark Energy Survey (OzDES) RM project based on six years of monitoring. We define quantitative criteria to select good lag measurements and verify their reliability with simulations based on both the damped random walk stochastic model and the re-scaled, re-sampled versions of the observed lightcurves of local, well-measured AGN. Our sample significantly increases the number of Mg II lags and extends the R - L relation to higher redshifts and luminosities. The relative iron line strength $\mathcal {R}_{\rm Fe}$ has little impact on the R - L relation. The best-fit Mg II R - L relation has a slope = 0.39 0.08 with an intrinsic scatter $\sigma _{\rm rl} = 0.15^{+0.03}_{-0.02}$. The slope is consistent with previous measurements and shallower than the H R - L relation. The intrinsic scatter of the new R - L relation is substantially smaller than previous studies and comparable to the intrinsic scatter of the H R - L relation. Our new R - L relation will enable more precise single-epoch mass estimates and SMBH demographic studies at cosmic noon.
  27. de Leon, J., Licandro, J., Pinilla-Alonso, N., et al., 2023, A&A, 672, A174, Characterisation of the new target of the NASA Lucy mission: Asteroid 152830 Dinkinesh (1999 VD57)
    Context. The NASA Lucy mission is designed to collect data that will be used to study the very interesting population of Jupiter Trojans, which are considered to be time capsules from the time of birth of our Solar System. During its journey, the mission will pass near a main belt asteroid, Donaldjohanson. Recently, NASA announced that a new asteroid in the belt will also be visited by Lucy: 152830 Dinkinesh (1999 VD57).
    Aims: The main goal of this work is to characterise this newly selected target, asteroid Dinkinesh, in order to provide critical information to the mission team. This information includes the most likely surface composition, albedo, and size of the asteroid, which will be used to better plan the data acquisition strategy at the time of the fly-by.
    Methods: To this end, we obtained visible spectra, colour photometry, and time-series photometry for Dinkinesh using several telescopes located at different observatories. For the spectra, we used the 10.4 m Gran Telescopio Canarias (GTC) on the island of La Palma (Spain); for the colour photometry, we used the 4.3 m Lowell Discovery Telescope (LDT) near Happy Jack, Arizona (USA); and for the time-series photometry, we used the 82 cm IAC80 telescope located on the island of Tenerife (Spain). We used the visible reflectance spectrum to obtain the taxonomical class of the asteroid in order to constrain its albedo value. Colour and time-series photometry were used to compute the absolute magnitude of Dinkinesh, which was used in conjunction with an albedo estimation to constrain its size.
    Results: Both the visible spectrum and reflectance values computed from colour photometry show that Dinkinesh is an S-type asteroid; that is, it is composed mainly of silicates and some metal. According to observations carried out as part of the NEOWISE survey, S-type asteroids have a typical geometric albedo of pV = 0.223 0.073. From our time-series photometry, we obtain an asteroid mean magnitude of r' = 19.99 0.05, which provides an absolute magnitude Hr' = 17.53 0.07 assuming G = 0.19 0.25 for S-types. Using our colour-photometry, we transformed Hr' to HV = 17.48 0.05. This value of absolute magnitude combined with the geometric albedo provides a mean diameter for Dinkinesh of ~900 m, ranging between a minimum size of 542 m and a maximum size of 1309 m.
  28. Abbott, T., Aguena, M., Alarcon, A., et al., 2023, PhRvD, 107, 083504, Dark Energy Survey Year 3 results: Constraints on extensions to CDM with weak lensing and galaxy clustering
    We constrain six possible extensions to the cold dark matter (CDM) model using measurements from the Dark Energy Survey's first three years of observations, alone and in combination with external cosmological probes. The DES data are the two-point correlation functions of weak gravitational lensing, galaxy clustering, and their cross-correlation. We use simulated data vectors and blind analyses of real data to validate the robustness of our results to astrophysical and modeling systematic errors. In many cases, constraining power is limited by the absence of theoretical predictions beyond the linear regime that are reliable at our required precision. The CDM extensions are dark energy with a time-dependent equation of state, nonzero spatial curvature, additional relativistic degrees of freedom, sterile neutrinos with eV-scale mass, modifications of gravitational physics, and a binned 8(z ) model which serves as a phenomenological probe of structure growth. For the time-varying dark energy equation of state evaluated at the pivot redshift we find (wp,wa)=(-0.9 9-0.17+0.28,-0.9 1.2 ) at 68% confidence with zp=0.24 from the DES measurements alone, and (wp,wa)=(-1.0 3-0.03+0.04,-0. 4-0.3+0.4) with zp=0.21 for the combination of all data considered. Curvature constraints of k=0.0009 0.0017 and effective relativistic species Neff=3.1 0-0.16+0.15 are dominated by external data, though adding DES information to external low-redshift probes tightens the k constraints that can be made without cosmic microwave background observables by 20%. For massive sterile neutrinos, DES combined with external data improves the upper bound on the mass meff by a factor of 3 compared to previous analyses, giving 95% limits of ( Neff,meff)(0.28 ,0.20 eV ) when using priors matching a comparable Planck analysis. For modified gravity, we constrain changes to the lensing and Poisson equations controlled by functions (k ,z )=0(z )/ ,0 and (k ,z )=0(z )/ ,0, respectively, to 0=0. 6-0.5+0.4 from DES alone and (0,0)=(0.04 0.05 ,0.0 8-0.19+0.21) for the combination of all data, both at 68% confidence. Overall, we find no significant evidence for physics beyond CDM .
  29. Loyd, R., Schneider, P., Jackman, J., et al., 2023, AJ, 165, 146, Flares, Rotation, Activity Cycles, and a Magnetic Star-Planet Interaction Hypothesis for the Far-ultraviolet Emission of GJ 436
    Variability in the far-ultraviolet (FUV) emission produced by stellar activity affects photochemistry and heating in orbiting planetary atmospheres. We present a comprehensive analysis of the FUV variability of GJ 436, a field-age M2.5V star (P rot 44 days) that is orbited by a warm Neptune-sized planet (M 25 M , R 4.1 M , P orb 2.6 days). Observations at three epochs from 2012 to 2018 span nearly a full activity cycle, sample two rotations of the star and two orbital periods of the planet, and reveal a multitude of brief flares. From 2012 to 2018, the star's 7.75 0.10 yr activity cycle produced the largest observed variations, 38% 3% in the summed flux of the major FUV emission lines. In 2018, the variability due to rotation was 8% 2%. An additional 11% 1% scatter at a cadence of 10 minutes, which is treated as white noise in the fits, likely has both instrumental and astrophysical origins. Flares increased time-averaged emission by 15% over the 0.88 days of cumulative exposure, peaking as high as 25 quiescence. We interpret these flare values as lower limits given that flares too weak or too infrequent to have been observed likely exist. GJ 436's flare frequency distribution at FUV wavelengths is unusual compared to other field-age M dwarfs, exhibiting a statistically significant dearth of high-energy (>4 1028 erg) events, which we hypothesize to be the result of a magnetic star-planet interaction (SPI) triggering premature flares. If an SPI is present, GJ 436 b's magnetic field strength must be 100 G to explain the statistically insignificant increase in the orbit-phased FUV emission.
  30. Quirico, E., Bacmann, A., Wolters, C., et al., 2023, Icar, 394, 115396, On a radiolytic origin of red organics at the surface of the Arrokoth Trans-Neptunian Object
    The classical Kuiper Belt Object (KBO) Arrokoth was surveyed by the New Horizons spacecraft on 1st January 2019, revealing a small bilobed object with a red surface, whose spectral slope lies in the average of the whole KBOs population. This red color has been assigned to reddish organic materials, either inherited from the protosolar disk during accretion, or formed through radiolytic processes in the surface due to exposure to solar or interstellar photons, Solar Wind, Solar Energetic Particles or Galactic Cosmic Rays. We report here a study investigating the radiolytic scenario, based on numerical calculations and experimental simulations run with swift heavy ions (74.8 MeV 136Xe19+ and 33.06 MeV 58Ni9+), and low-energy 105 keV 18O6+ ions on CH3OH ice, the only molecule identified at Arrokoth's surface. Calculations show that sputtering is essentially controlled by Solar Wind (H and He), and that the sputtering rate depends on the nature of the material: erosion thickness over 4.55 Gyr are a few micrometers for amorphous carbon (as an analog of red organics) and a 240 m to around 10 mm for H2O and CO ice, respectively. Chemistry within the subsurface is essentially controlled by Galactic Cosmic rays (H and He), which penetrate deep down to several tens of meters and deliver an electronic dose higher than 1 eV.atom-1 in the first meter. The electronic and elastic doses delivered by Solar Wind ions are limited to the first 10s nm of the top surface, but Solar Energetic Particles deliver high electronic doses in the first 100 m of the surface (up to 200 eV.atom-1). Experimental simulations show that irradiating methanol ice with a dose consistent with that in planetary conditions, results in the formation of reddish organic materials made of aliphatic, conjugated and unconjugated olefinic, acetylinic, carbonyl and hydroxyl groups. A similarity with irradiated simple polymers (e.g. polyethyleneglycol) and materials formed through cold plasma experiments (tholins) is observed. There is little dependence with the nature and energy of the ion. The residue recovered at room temperature was analyzed with High Resolution Mass Spectrometry (Orbitrap), revealing a complex composition with around 6596 chemical formulas and likely several tens of thousands of molecules. Altogether, these analyses support active polymerization mechanisms similar to those observed in irradiated polymers, as bond-breaking, cross-linking or formation of olefinic bonds through recombination of radicals in adjacent carbon atoms. Considering both sputtering and radiolysis, as well as material ablation due to dust bombardment reported in literature, a scenario is taking shape as the production of reddish organics deep in the subsurface, and the settling of an organic crust at the top surface through volatiles removal. The presence of methanol and absence of water, inconsistent with sputtering fractionation, remains unexplained.
  31. Malik, U., Sharp, R., Penton, A., et al., 2023, MNRAS, 520, 2009, OzDES Reverberation Mapping Program: H lags from the 6-yr survey
    Reverberation mapping measurements have been used to constrain the relationship between the size of the broad-line region and luminosity of active galactic nuclei (AGN). This R-L relation is used to estimate single-epoch virial black hole masses, and has been proposed to use to standardize AGN to determine cosmological distances. We present reverberation measurements made with H from the 6-yr Australian Dark Energy Survey (OzDES) Reverberation Mapping Program. We successfully recover reverberation lags for eight AGN at 0.12 < z < 0.71, probing higher redshifts than the bulk of H measurements made to date. Our fit to the R-L relation has a slope of = 0.41 0.03 and an intrinsic scatter of = 0.23 0.02 dex. The results from our multi-object spectroscopic survey are consistent with previous measurements made by dedicated source-by-source campaigns, and with the observed dependence on accretion rate. Future surveys, including LSST, TiDES, and SDSS-V, which will be revisiting some of our observed fields, will be able to build on the results of our first-generation multi-object reverberation mapping survey.
  32. Kueny, J., Chandler, C., Devogele, M., et al., 2023, PSJ, 4, 56, Implications for the Formation of (155140) 2005 UD from a New Convex Shape Model
    (155140) 2005 UD has a similar orbit to (3200) Phaethon, an active asteroid in a highly eccentric orbit thought to be the source of the Geminid meteor shower. Evidence points to a genetic relationship between these two objects, but we have yet to fully understand how 2005 UD and Phaethon could have separated into this associated pair. Presented herein are new observations of 2005 UD from five observatories that were carried out during the 2018, 2019, and 2021 apparitions. We implemented light curve inversion using our new data, as well as dense and sparse archival data from epochs in 2005-2021, to better constrain the rotational period and derive a convex shape model of 2005 UD. We discuss two equally well-fitting pole solutions ( = 116.6, = -53.6) and ( = 300.3, = -55.4), the former largely in agreement with previous thermophysical analyses and the latter interesting due to its proximity to Phaethon's pole orientation. We also present a refined sidereal period of P sid = 5.234246 0.000097 hr. A search for surface color heterogeneity showed no significant rotational variation. An activity search using the deepest stacked image available of 2005 UD near aphelion did not reveal a coma or tail but allowed modeling of an upper limit of 0.04-0.37 kg s-1 for dust production. We then leveraged our spin solutions to help limit the range of formation scenarios and the link to Phaethon in the context of nongravitational forces and timescales associated with the physical evolution of the system.
  33. Cartwright, R., DeColibus, D., C. Castillo-Rogez, J., et al., 2023, PSJ, 4, 42, Evidence for Nitrogen-bearing Species on Umbriel: Sourced from a Subsurface Ocean, Undifferentiated Crust, or Impactors?
    Near-infrared spectra of Umbriel and the other classical Uranian moons exhibit 2.2 m absorption bands that could result from ammonia (NH3) bearing species, possibly exposed in the geologically recent past. However, Umbriel has an ancient surface with minimal evidence for recent endogenic activity, raising the possibility that more refractory species are present, and/or that NH3 is retained over long timescales. We analyzed 33 spectra of Umbriel to investigate its 2.2 m band, along with three other absorption features we identified near 2.14, 2.22, and 2.24 m. We assessed the subobserver longitudinal distributions of these four bands, finding that they are present across Umbriel and may be spatially associated with geologic features such as craters and large basins. We compared the bands to 15 candidate constituents. We found that Umbriel's 2.14 m and 2.22 m bands are most consistent with the spectral signature of organics, its 2.24 m band is best matched by NH3 ice, and its 2.2 m band is consistent with the signatures of NH3-H2O mixtures, aluminum-bearing phyllosilicates, and sodium-bearing carbonates. However, some of these candidate constituents do not match Umbriel's spectral properties in other wavelength regions, highlighting the gaps in our understanding of the Uranian moons' surface compositions. Umbriel's 2.14 m band may alternatively result from a 2 3 overtone mode of CO2 ice. If present on Umbriel, these candidate constituents could have formed in contact with an internal ocean and were subsequently exposed during Umbriel's early history. Alternatively, these constituents might have originated in an undifferentiated crust or were delivered by impactors.
  34. Shrestha, M., Sand, D., Alexander, K., et al., 2023, ApJL, 946, L25, Limit on Supernova Emission in the Brightest Gamma-Ray Burst, GRB 221009A
    We present photometric and spectroscopic observations of the extraordinary gamma-ray burst (GRB) 221009A in search of an associated supernova. Some past GRBs have shown bumps in the optical light curve that coincide with the emergence of supernova spectral features, but we do not detect any significant light-curve features in GRB 221009A, nor do we detect any clear sign of supernova spectral features. Using two well-studied GRB-associated supernovae (SN 2013dx, ${M}_{r,\max }=-19.54;$ SN 2016jca, ${M}_{r,\max }=-19.04$ ) at a similar redshift as GRB 221009A (z = 0.151), we modeled how the emergence of a supernova would affect the light curve. If we assume the GRB afterglow to decay at the same rate as the X-ray data, the combination of afterglow and a supernova component is fainter than the observed GRB brightness. For the case where we assume the best-fit power law to the optical data as the GRB afterglow component, a supernova contribution should have created a clear bump in the light curve, assuming only extinction from the Milky Way. If we assume a higher extinction of E(B - V) = 1.74 mag (as has been suggested elsewhere), the supernova contribution would have been hard to detect, with a limit on the associated supernova of ${M}_{r,\max }\approx -$ 19.54. We do not observe any clear supernova features in our spectra, which were taken around the time of expected maximum light. The lack of a bright supernova associated with GRB 221009A may indicate that the energy from the explosion is mostly concentrated in the jet, leaving a lower energy budget available for the supernova.
  35. Zhao, L., Kunovac, V., Brewer, J., et al., 2023, NatAs, 7, 366, Author Correction: Measured spin-orbit alignment of ultra-short-period super-Earth 55 Cancri e
  36. Bowen, B., Reddy, V., De Florio, M., et al., 2023, PSJ, 4, 52, Grain Size Effects on Visible and Near-infrared (0.35-2.5 m) Laboratory Spectra of Ordinary Chondrite and HED Meteorites
    Remote spectral characterization of near-Earth asteroids (NEAs) relies on laboratory spectral calibration to constrain their surface composition, including mineral chemistry and relative mineral abundances. Often these calibrations are based on fine meteorite powders that are representative of regolith observed on large NEAs such as (433) Eros. However, spacecraft observations of smaller NEAs such as (25143) Itokawa, (101955) Bennu, and (162173) Ryugu show surfaces devoid of a thick layer of regolith and instead find variegated landscapes with millimeter-sized particles to meter-scale boulders. Here we present the results of a laboratory study to understand the effects of grain size on the spectral properties of meteorites and how this can impact ground-based characterization of NEAs. Our study focuses on ordinary chondrites (H, L, LL) and HED meteorites, as they comprise ~90% of all meteorites that fall on Earth. Compared to ordinary chondrites, the spectral band parameters of HED meteorites are less affected by changing grain size. Among the ordinary chondrites, LL chondrites are least affected, but the spectral band parameters and mineral chemistries and abundances for H and L chondrites are most affected by changing grain size. Grain size does not seem to have any significant effect on the taxonomic classification of our meteorite spectra. We also used the Hapke model to investigate trends in single-scattering albedo as a function of grain size and present equations to recover the grain size from a spectrum.
  37. Chandler, C., Oldroyd, W., Hsieh, H., et al., 2023, RNAAS, 7, 60, New Recurrently Active Main-belt Comet 2010 LH15
    We announce the discovery of a main-belt comet (MBC), 2010 LH15 (alternately designated 2010 TJ175). MBCs are a rare type of main-belt asteroid that display comet-like activity, such as tails or comae, caused by sublimation. Consequently, MBCs help us map the location of solar system volatiles, providing insight into the origins of material prerequisite for life as we know it. However, MBCs have proven elusive, with fewer than 20 found among the 1.1 million known main-belt asteroids. This finding derives from Active Asteroids, a NASA Partner Citizen Science program we designed to identify more of these important objects. After volunteers classified an image of 2010 LH15 as showing activity, we carried out a follow-up investigation which revealed evidence of activity from two epochs spanning nearly a decade. This discovery is timely, with 2010 LH15 inbound toward its 2024 March perihelion passage, with potential activity onset as early as late 2023.
  38. Hsieh, H., Micheli, M., Kelley, M., et al., 2023, PSJ, 4, 43, Observational Characterization of Main-belt Comet and Candidate Main-belt Comet Nuclei
    We report observations of nine main-belt comets (MBCs) or candidate MBCs, most of which were obtained when the targets were apparently inactive. We find effective nucleus radii (assuming albedos of p V = 0.05 0.02) of r n = (0.24 0.05) km for 238P/Read, r n = (0.9 0.2) km for 313P/Gibbs, r n = (0.6 0.1) km for 324P/La Sagra, r n = (1.0 0.2) km for 426P/PANSTARRS, r n = (0.5 0.1) km for 427P/ATLAS, r n < (0.3 0.1) km for P/2016 J1-A (PANSTARRS), r n < (0.17 0.04) km for P/2016 J1-B (PANSTARRS), r n (0.5 0.2) km for P/2017 S9 (PANSTARRS), recently redesignated 455P/PANSTARRS, and r n = (0.4 0.1) km for P/2019 A3 (PANSTARRS). We identify evidence of activity in observations of 238P in 2021, and find similar inferred activity onset times and net initial mass-loss rates for 238P during perihelion approaches in 2010, 2016, and 2021. P/2016 J1-A and P/2016 J1-B are also found to be active in 2021 and 2022, making them collectively the tenth MBC confirmed to be recurrently active near perihelion and therefore likely to be exhibiting sublimation-driven activity. The nucleus of 313P is found to have colors of $g^{\prime} -r^{\prime} =0.52\pm 0.05$ and $r^{\prime} -i^{\prime} =0.22\pm 0.07$ , consistent with 313P being a Lixiaohua family member. We also report nondetections of P/2015 X6 (PANSTARRS), where we conclude that its current nucleus size is likely below our detection limits (r n 0.3 km). Lastly, we find that of 17 MBCs or candidate MBCs for which nucleus sizes (or inferred parent body sizes) have been estimated, >80% have r n 1.0 km, pointing to an apparent physical preference toward small MBCs, where we suggest that Yarkovsky-O'Keefe-Radzievskii-Paddack spin-up may play a significant role in triggering and/or facilitating MBC activity.
  39. Velloso, E., Anthony, F., do Nascimento, J., et al., 2023, ApJL, 945, L12, Multicomponent Activity Cycles Using Hilbert-Huang Analysis
    The temporal analysis of stellar activity evolution is usually dominated by a complex trade-off between model complexity and interpretability, often by neglecting the nonstationary nature of the process. Recent studies appear to indicate that the presence of multiple coexisting cycles in a single star is more common than previously thought. The correct identification of physically meaningful cyclic components in spectroscopic time series is therefore a crucial task, which cannot overlook local behaviors. Here we propose a decomposition technique that adaptively recovers amplitude- and frequency-varying components. We present our results for the solar activity as measured both by the sunspot number and the K-line emission index, and we consistently recover the Schwabe and Gleissberg cycles as well as the Gnevyshev-Ohl pattern probably related to the Hale cycle. We also recover the known 8 yr cycle for 61 Cygni A, in addition to evidence of a three-cycles-long pattern reminiscent of the Gnevyshev-Ohl rule. This is particularly interesting as we cannot discard the possibility of a relationship between the measured field polarity reversals and this Hale-like periodicity.
  40. Oldroyd, W., Chandler, C., Trujillo, C., et al., 2023, RNAAS, 7, 42, Comet-like Activity Discovered on Quasi-Hilda Asteroid 2009 DQ118
    We report evidence of comet-like activity on asteroid 2009 DQ118, a quasi-Hilda object near the 3:2 interior mean-motion resonance with Jupiter. This discovery was made by volunteers as part of the Active Asteroids Citizen Science project, a NASA Partner hosted on the Zooniverse platform. Follow-up archival searches yielded over 20 images of 2009 DQ118 exhibiting a comet-like tail on UT 2016 March 8 and 9 acquired with the Dark Energy Camera on the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory, Chile. These images were taken when 2009 DQ118 was near its 2016 perihelion passage. 2009 DQ118 will next reach perihelion on UT 2023 April 22; hence, the next several months are an excellent time to observe 2009 DQ118 to search for a second epoch of activity for this object.
  41. Grayling, M., Gutierrez, C., Sullivan, M., et al., 2023, MNRAS, 520, 684, Core-collapse supernovae in the Dark Energy Survey: luminosity functions and host galaxy demographics
    We present the luminosity functions and host galaxy properties of the Dark Energy Survey (DES) core-collapse supernova (CCSN) sample, consisting of 69 Type II and 50 Type Ibc spectroscopically and photometrically confirmed supernovae over a redshift range 0.045 < z < 0.25. We fit the observed DES griz CCSN light curves and K-correct to produce rest-frame R-band light curves. We compare the sample with lower redshift CCSN samples from Zwicky Transient Facility (ZTF) and Lick Observatory Supernova Search (LOSS). Comparing luminosity functions, the DES and ZTF samples of SNe II are brighter than that of LOSS with significances of 3.0 and 2.5, respectively. While this difference could be caused by redshift evolution in the luminosity function, simpler explanations such as differing levels of host extinction remain a possibility. We find that the host galaxies of SNe II in DES are on average bluer than in ZTF, despite having consistent stellar mass distributions. We consider a number of possibilities to explain this - including galaxy evolution with redshift, selection biases in either the DES or ZTF samples, and systematic differences due to the different photometric bands available - but find that none can easily reconcile the differences in host colour between the two samples and thus its cause remains uncertain.
  42. Sebastian, D., Swayne, M., Maxted, P., et al., 2023, MNRAS, 519, 3546, The EBLM project - IX. Five fully convective M-dwarfs, precisely measured with CHEOPS and TESS light curves
    Eclipsing binaries are important benchmark objects to test and calibrate stellar structure and evolution models. This is especially true for binaries with a fully convective M-dwarf component for which direct measurements of these stars' masses and radii are difficult using other techniques. Within the potential of M-dwarfs to be exoplanet host stars, the accuracy of theoretical predictions of their radius and effective temperature as a function of their mass is an active topic of discussion. Not only the parameters of transiting exoplanets but also the success of future atmospheric characterization relies on accurate theoretical predictions. We present the analysis of five eclipsing binaries with low-mass stellar companions out of a subsample of 23, for which we obtained ultra-high-precision light curves using the CHEOPS satellite. The observation of their primary and secondary eclipses are combined with spectroscopic measurements to precisely model the primary parameters and derive the M-dwarfs mass, radius, surface gravity, and effective temperature estimates using the PYCHEOPS data analysis software. Combining these results to the same set of parameters derived from TESS light curves, we find very good agreement (better than 1 per cent for radius and better than 0.2 per cent for surface gravity). We also analyse the importance of precise orbits from radial velocity measurements and find them to be crucial to derive M-dwarf radii in a regime below 5 per cent accuracy. These results add five valuable data points to the mass-radius diagram of fully convective M-dwarfs.
  43. Jackman, J., Shkolnik, E., Million, C., et al., 2023, MNRAS, 519, 3564, Extending optical flare models to the UV: results from comparing of TESS and GALEX flare observations for M Dwarfs
    The ultraviolet (UV) emission of stellar flares may have a pivotal role in the habitability of rocky exoplanets around low-mass stars. Previous studies have used white-light observations to calibrate empirical models which describe the optical and UV flare emission. However, the accuracy of the UV predictions of models has previously not been tested. We combined TESS optical and GALEX UV observations to test the UV predictions of empirical flare models calibrated using optical flare rates of M stars. We find that the canonical 9000-K black-body model used by flare studies underestimates the GALEX near-ultraviolet (NUV) energies of field age M stars by up to a factor of 6.5 0.7 and the GALEX far-ultraviolet energies of fully convective field age M stars by 30.6 10.0. We calculated energy correction factors that can be used to bring the UV predictions of flare models closer in line with observations. We calculated pseudo-continuum flare temperatures that describe both the white-light and GALEX NUV emission. We measured a temperature of 10 700 K for flares from fully convective M stars after accounting for the contribution from UV line emission. We also applied our correction factors to the results of previous studies of the role of flares in abiogenesis. Our results show that M stars do not need to be as active as previously thought in order to provide the NUV flux required for prebiotic chemistry, however, we note that flares will also provide more FUV flux than previously modelled.
  44. Radhakrishnan, V., Keller, C., Doelman, N., et al., 2023, A&A, 670, A137, Estimating non-common path aberrations with an adaptive coronagraph
    Context. The focal-plane contrast of exoplanet imagers is affected by non-common path aberrations (NCPAs) that the adaptive optics system cannot correct for because they occur after the wavefront has been measured. NCPA estimation is commonly based on the long-exposure science image. Phase retrieval algorithms are often used, and they mostly assume that the residual phase error right after the adaptive optics system and averaged over the integration time is zero. This assumption is not always correct, for instance when controlling the adaptive optics to maximize the focal-plane contrast at the location of an exoplanet, that is to say in an adaptive coronagraph. For such cases, we present a method to calculate the NCPA using the phase information derived from the wavefront sensor (WFS) data and the science focal-plane image.
    Aims: We aim to accurately estimate the NCPA phase in the presence of (residual) atmospheric turbulence with a nonzero average wavefront. We then aim to take the NCPA into account in the adaptive coronagraph controller and achieve a higher contrast.
    Methods: The WFS measures the wavefront throughout the integration time of the science image. We combine information from the recorded WFS phases to remove the effects of the nonzero average phase from the Point Spread Function (PSF) and to remove the effects of the residual turbulence averaging over time. Then we estimate the NCPA by applying a phase-diversity-based algorithm to the resulting images. Our method is currently limited to imagers with pupil-plane coronagraphs.
    Results: We are able to recover the NCPA in an adaptive coronagraph setting with 0.01 radian RMS residuals and with a residual turbulence phase error of approximately 0.4 radian RMS. When accounted for in a contrast-control scheme, the NCPA correction leads to an order of magnitude improvement of contrast and a 50% increase in Strehl ratio, in numerical simulations.
  45. Zhao, L., Kunovac, V., Brewer, J., et al., 2023, NatAs, 7, 198, Measured spin-orbit alignment of ultra-short-period super-Earth 55 Cancri e
    A planet's orbital alignment places important constraints on how a planet formed and consequently evolved. The dominant formation pathway of ultra-short-period planets (P < 1 day) is particularly mysterious as such planets most likely formed further out, and it is not well understood what drove their migration inwards to their current positions. Measuring the orbital alignment is difficult for smaller super-Earth/sub-Neptune planets, which give rise to smaller amplitude signals. Here we present radial velocities across two transits of 55 Cancri (Cnc) e, an ultra-short-period super-Earth, observed with the Extreme Precision Spectrograph. Using the classical Rossiter-McLaughlin method, we measure 55 Cnc e's sky-projected stellar spin-orbit alignment (that is, the projected angle between the planet's orbital axis and its host star's spin axis) to be =10-20+17 with an unprojected angle of =23-12+14. The best-fit Rossiter-McLaughlin model to the Extreme Precision Spectrograph data has a radial velocity semi-amplitude of just 0.41-0.10+0.09 m s1. The spin-orbit alignment of 55 Cnc e favours dynamically gentle migration theories for ultra-short-period planets, namely tidal dissipation through low-eccentricity planet-planet interactions and/or planetary obliquity tides.
  46. Schiappucci, E., Bianchini, F., Aguena, M., et al., 2023, PhRvD, 107, 042004, Measurement of the mean central optical depth of galaxy clusters via the pairwise kinematic Sunyaev-Zel'dovich effect with SPT-3G and DES
    We infer the mean optical depth of a sample of optically selected galaxy clusters from the Dark Energy Survey via the pairwise kinematic Sunyaev-Zel'dovich (KSZ) effect. The pairwise KSZ signal between pairs of clusters drawn from the Dark Energy Survey Year-3 cluster catalog is detected at 4.1 in cosmic microwave background temperature maps from two years of observations with the SPT-3G camera on the South Pole Telescope. After cuts, there are 24,580 clusters in the 1 ,400 deg2 of the southern sky observed by both experiments. We infer the mean optical depth of the cluster sample with two techniques. The optical depth inferred from the pairwise KSZ signal is e=(2.97 0.73 )10-3 , while that inferred from the thermal SZ signal is e=(2.51 0.5 5stat0.1 5syst)10-3 . The two measures agree at 0.6 . We perform a suite of systematic checks to test the robustness of the analysis.
  47. Chandler, C., Oldroyd, W., Trujillo, C., et al., 2023, RNAAS, 7, 27, New Active Asteroid 2015 VA108: A Citizen Science Discovery
    We announce the discovery of activity, in the form of a distinct cometary tail, emerging from main-belt asteroid 2015 VA108. Activity was first identified by volunteers of the Citizen Science project Active Asteroids (a NASA Partner). We uncovered one additional image from the same observing run which also unambiguously shows 2015 VA108 with a tail oriented between the anti-solar and anti-motion vectors that are often correlated with activity orientation on sky. Both publicly available archival images were originally acquired UT 2015 October 11 with the Dark Energy Camera (DECam) on the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory (Chile) as part of the Dark Energy Camera Legacy Survey. Activity occurred near perihelion and, combined with its residence in the main asteroid belt, 2015 VA108 is a candidate main-belt comet, an active asteroid subset known for volatile sublimation.
  48. Simon, J., Brown, T., Mutlu-Pakdil, B., et al., 2023, ApJ, 944, 43, Timing the r-process Enrichment of the Ultra-faint Dwarf Galaxy Reticulum II
    The ultra-faint dwarf galaxy Reticulum II (Ret II) exhibits a unique chemical evolution history, with ${72}_{-12}^{+10}$ % of its stars strongly enhanced in r-process elements. We present deep Hubble Space Telescope photometry of Ret II and analyze its star formation history. As in other ultra-faint dwarfs, the color-magnitude diagram is best fit by a model consisting of two bursts of star formation. If we assume that the bursts were instantaneous, then the older burst occurred around the epoch of reionization, forming ~80% of the stars in the galaxy, while the remainder of the stars formed ~3 Gyr later. When the bursts are allowed to have nonzero durations, we obtain slightly better fits. The best-fitting model in this case consists of two bursts beginning before reionization, with approximately half the stars formed in a short (100 Myr) burst and the other half in a more extended period lasting 2.6 Gyr. Considering the full set of viable star formation history models, we find that 28% of the stars formed within 500 200 Myr of the onset of star formation. The combination of the star formation history and the prevalence of r-process-enhanced stars demonstrates that the r-process elements in Ret II must have been synthesized early in its initial star-forming phase. We therefore constrain the delay time between the formation of the first stars in Ret II and the r-process nucleosynthesis to be less than 500 Myr. This measurement rules out an r-process source with a delay time of several Gyr or more, such as GW170817.
  49. Chandler, C., Trujillo, C., Oldroyd, W., et al., 2023, RNAAS, 7, 22, Discovery of Dust Emission Activity Emanating from Main-belt Asteroid 2015 FW412
    We present the discovery of activity emanating from main-belt asteroid 2015 FW412, a finding stemming from the Citizen Science project Active Asteroids, a NASA Partner program. We identified a pronounced tail originating from 2015 FW412 and oriented in the anti-motion direction in archival Blanco 4 m (Cerro Tololo Inter-American Observatory, Chile) Dark Energy Camera images from UT 2015 April 13, 18, 19, 21 and 22. Activity occurred near perihelion, consistent with the main-belt comets (MBCs), an active asteroid subset known for sublimation-driven activity in the main asteroid belt; thus 2015 FW412 is a candidate MBC. We did not detect activity on UT 2021 December 12 using the Inamori-Magellan Areal Camera and Spectrograph on the 6.5 m Baade telescope, when 2015 FW412 was near aphelion.
  50. Baines, E., Blomquist, S., Clark, J., et al., 2023, AJ, 165, 41, Simultaneous Six-way Observations from the Navy Precision Optical Interferometer
    We measured the angular diameters of six stars using the six-element observing mode of the Navy Precision Optical Interferometer (NPOI) for the first time since the early 2000s. Four of the diameters ranged from 1.2 to 1.9 mas, while the two others were much smaller at approximately 0.5 mas to 0.7 mas, which are the two smallest angular diameters measured to date with the NPOI. There is a larger spread in the measurements than data obtained with three-, four-, or five-element modes, which can be attributed in part to the flux imbalance due to the combination of more than two siderostats in a single spectrograph, and also to crosstalk between multiple baselines related to nonlinearities in the fast-delay-line dither strokes. We plan to address this in the future by using the VISION beam combiner.
  51. Kelsey, L., Sullivan, M., Wiseman, P., et al., 2023, MNRAS, 519, 3046, Concerning colour: The effect of environment on type Ia supernova colour in the dark energy survey
    Recent analyses have found intriguing correlations between the colour (c) of type Ia supernovae (SNe Ia) and the size of their 'mass-step', the relationship between SN Ia host galaxy stellar mass (Mstellar) and SN Ia Hubble residual, and suggest that the cause of this relationship is dust. Using 675 photometrically classified SNe Ia from the Dark Energy Survey 5-yr sample, we study the differences in Hubble residual for a variety of global host galaxy and local environmental properties for SN Ia subsamples split by their colour. We find a 3 difference in the mass-step when comparing blue (c < 0) and red (c > 0) SNe. We observe the lowest r.m.s. scatter (~0.14 mag) in the Hubble residual for blue SNe in low mass/blue environments, suggesting that this is the most homogeneous sample for cosmological analyses. By fitting for c-dependent relationships between Hubble residuals and Mstellar, approximating existing dust models, we remove the mass-step from the data and find tentative ~2 residual steps in rest-frame galaxy U - R colour. This indicates that dust modelling based on Mstellar may not fully explain the remaining dispersion in SN Ia luminosity. Instead, accounting for a c-dependent relationship between Hubble residuals and global U - R, results in 1 residual steps in Mstellar and local U - R, suggesting that U - R provides different information about the environment of SNe Ia compared to Mstellar, and motivating the inclusion of galaxy U - R colour in SN Ia distance bias correction.
  52. Myles, J., Gruen, D., Amon, A., et al., 2023, MNRAS, 519, 1792, Mapping variations of redshift distributions with probability integral transforms
    We present a method for mapping variations between probability distribution functions and apply this method within the context of measuring galaxy redshift distributions from imaging survey data. This method, which we name PITPZ for the probability integral transformations it relies on, uses a difference in curves between distribution functions in an ensemble as a transformation to apply to another distribution function, thus transferring the variation in the ensemble to the latter distribution function. This procedure is broadly applicable to the problem of uncertainty propagation. In the context of redshift distributions, for example, the uncertainty contribution due to certain effects can be studied effectively only in simulations, thus necessitating a transfer of variation measured in simulations to the redshift distributions measured from data. We illustrate the use of PITPZ by using the method to propagate photometric calibration uncertainty to redshift distributions of the Dark Energy Survey Year 3 weak lensing source galaxies. For this test case, we find that PITPZ yields a lensing amplitude uncertainty estimate due to photometric calibration error within 1 per cent of the truth, compared to as much as a 30 per cent underestimate when using traditional methods.
  53. Chen, A., Arico, G., Huterer, D., et al., 2023, MNRAS, 518, 5340, Constraining the baryonic feedback with cosmic shear using the DES Year-3 small-scale measurements
    We use the small scales of the Dark Energy Survey (DES) Year-3 cosmic shear measurements, which are excluded from the DES Year-3 cosmological analysis, to constrain the baryonic feedback. To model the baryonic feedback, we adopt a baryonic correction model and use the numerical package BACCOEMU to accelerate the evaluation of the baryonic non-linear matter power spectrum. We design our analysis pipeline to focus on the constraints of the baryonic suppression effects, utilizing the implication given by a principal component analysis on the Fisher forecasts. Our constraint on the baryonic effects can then be used to better model and ameliorate the effects of baryons in producing cosmological constraints from the next-generation large-scale structure surveys. We detect the baryonic suppression on the cosmic shear measurements with a ~2 significance. The characteristic halo mass for which half of the gas is ejected by baryonic feedback is constrained to be $M_c \gt 10^{13.2} \, h^{-1} \, \mathrm{M}_{\odot }$ (95 per cent C.L.). The best-fitting baryonic suppression is $\sim 5{{\ \rm per\ cent}}$ at $k=1.0 \, {\rm Mpc}\ h^{-1}$ and $\sim 15{{\ \rm per\ cent}}$ at $k=5.0 \, {\rm Mpc} \ h^{-1}$. Our findings are robust with respect to the assumptions about the cosmological parameters, specifics of the baryonic model, and intrinsic alignments.
  54. Bartlett, J., Trimble, V., Griffin, R., et al., 2023, AAS, 55, 99.01, Got Stuff? How We Deal with Possible Astronomical Heritage Material
    According to the adage, "One person's trash is another's treasure." When we finish a project, some resources will continue to be significant for our future research while others may no longer be relevant. How do we decide personally what is trash and what is treasure? What is our responsibility to those who might treasure our trash? While cheap, digital storage is available, retaining the bits is easy to do. For our predecessors who recorded their observations on tapes, glass plates, or paper, storage was a greater challenge. Over time, many raw observations and working notes have been discarded. Once an observation is lost, we can never recapture that unique view of space and time. While we cannot know what questions future astronomers will ask, we can envision its reuse, along with its associated metadata and algorithms. Neither raw observations nor scientific results exist without an entire ecosystem of instruments and institutions. For these, too, we must assess their status as trash or treasure and, for treasure, assign responsibility. What about instruments that have been superseded or observatory sites that have outlived their original mission? What retains scientific value? What can be re-purposed for education or outreach? What has continuing historic and cultural importance? Furthermore, we cannot and should not preserve everything; how, then, do we choose what to preserve and how best to conserve it? The AAS charged its Working Group on the Preservation of Astronomical Heritage (WGPAH) with establishing criteria and priorities for identifying heritage material and with disseminating best practices for preserving heritage resources so that our scientific legacy remains available for research, teaching, and outreach. WGPAH can help you realistically sort through the trash and treasure of astronomical research. The choices we make reflect our values and reveal the stories we want to tell ourselves. Because our scientific heritage belongs to our whole community, we welcome your participation to ensure we preserve as many stories as we can.
  55. Lincoln, E., Baron, F., van Belle, G., 2023, AAS, 55, 105.21, The Pursuit of Hierarchies: Using improved speckle algorithms to investigate high-order stellar multiples
    Results are presented from a Fall 2022 observing run on the 4.3m Lowell Discovery Telescope (LDT) searching for previously unresolved binaries with the speckle imager QWSSI as well as results from the 3.5m WIYN telescope using the speckle imager NESSI. 25 targets were selected from a list of 91 K dwarfs within 33pc that showed variable radial velocity (RV) but have not previously been spatially resolved. Using a new algorithm that combines blind deconvolution and model fitting, we can determine accurate solutions for both the position and flux ratio of these binaries, as well as probe the surrounding pixels for faint companions. K dwarfs have a multiplicity rate of 40%, with 10% the population expected to be in triple or higher-order systems. Of the 190 total targets observed to determine RV, 91 targets showed variable RV, indicating multiplicity, and two of those targets are known triples. The inferred multiplicity fraction is slightly higher than expected, but with just 2 of 190 targets in spatially resolved triple systems, only 1% of this population has been found to be in a triple or higher-order system compared to the expected 10%. In our results, we expect all 25 targets to show multiplicity, and we expect to find 3 targets with two or more companions. To validate the companion detection efficiency of this new speckle reduction algorithm, five known binaries and the two known triples were chosen from this list as control targets. Using datasets obtained from WIYN and NESSI, we compare the performance of the conventional speckle interferometry pipeline with the blind deconvolution pipeline our group is developing.
  56. Prato, L., Tofflemire, B., Krolikowski, D., et al., 2023, AAS, 55, 106.14, Orbits and Disks of the Young Double-Lined Spectroscopic Binaries StH 34 and V562 Ori
    StH 34 (HBC 425) and V562 Ori (JW 707) are short-period, pre-main sequence spectroscopic binaries in the Taurus and Orion star-forming regions, respectively. Both systems host circumbinary disks; in StH 34, active accretion is occurring onto one or both stars. These relatively rare double-lined, disk-bearing systems provide the opportunity to study disk structure and evolution and the accretion process in complex environments, yielding clues to the dynamics of accretion onto massive planets and to disk dissipation. We obtained echelle spectra in visible light using the McDonald Observatory Harlan J. Smith 2.7 meter telescope with the Tull spectrograph and in the near-infrared using the Lowell Discovery Telescope with the IGRINS spectrograph. With these data we measure stellar radial velocities using a spectral-line broadening function analysis and cross-correlation, and solve for the binary orbital parameters. Time-series spectra used to characterize the orbit of StH 34 (P=21 days, mass ratio ~1, mid-M spectral types, e=0.6) reveal a complex H emission line profile; the system's K2 light curve shows "dipper" behavior. We explore correlations between the orbital and gas dynamics in this young binary and find that its variability is more stochastic than the predictable periastron accretion bursts seen in the binary-accretion archetype, DQ Tau. These differences, possibly the result of the higher accretion rate in StH 34, allow us to probe the binary-disk interaction in a new regime. For V562 Ori (P=12 days, mass ratio ~1, mid-K spectral types, e=0.1), a lack of near-infrared excess in the system indicates no warm dust in close proximity to the stars and no apparent accretion; however, 3.6 and 4.5 micron data from the YSOVARS program demonstrate the presence of cool circumbinary dust. Variability in the brightness and color of the mid-infrared excess appears to correlate with the orbital period. This research was supported in part by NSF awards AST-1313399 and AST-1518081.
  57. Adams, D., 2023, AAS, 55, 121.01, From Diving Eagle to Alighting Vulture: The Origin of Vega in Arabian Astronomy
    The bright star Vega has a name that is well-known around the world, but whose meaning continues to be misunderstood. Typically presented as the "Diving Eagle", the original Arabic name for Vega an-nasr al-waqi is best interpreted as the "Alighting Vulture". Together with its partner, Altairthe Flying Vulturethese two stars were well-known to Arabian astronomy as the Two Vultures, a star name that was in use by the early 6th century CE.

    Drawing from 6th century CE pre-Islamic Arabic poetry and 9th and 10th century CE Arabic texts by Qutrub (d. 821 CE), Ibn Qutayba (d. 889 CE), and as-Sufi (d. 986 CE), this talk traces the origins and significance of the Two Vultures in indigenous Arabian astronomy and reveals the time of night and season of the year during which they were intended to be observed. This original research demonstrates the benefit of fully understanding the cultural contexts out of which even the most prominent of our modern star names have come.

  58. Massey, P., Neugent, K., Ekstrom, S., 2023, AAS, 55, 127.06, Using Luminosity Functions to Determine the Mass-Loss Rates of Red Supergiants
    One of the main uncertainties in modeling the evolution of massive stars is accounting for mass loss during the red supergiant (RSG) phase. Such mass loss shortens the lifetime of the RSG phase, and, at high values, results in these stars shedding their hydrogen-rich outer layers and evolving back towards higher temperatures before ending their lives as supernovae. It also changes the distribution of SN types expected, and possibly even the sort of compact objects left behind, depending upon how much mass is lost during earlier phases. We can measure the mass-loss rates of RSGs using IR fluxes, but these only give us the rate today. Yet, RSGs lose mass primarily episodically, as revealed by such events as the recent Great Dimming of Betelgeuse. The current generation of Geneva evolutionary models address this problem by increasing the mass-loss rates by a factor of 3 over the quiescent rates whenever the outer envelopes of their models exceed the Eddington luminosity by a factor of 5. Including these "outbursts" has the effect of increasing the amount of mass lost by a 20 solar-mass RSG by a factor of 10 integrated over the star's lifetime. There is little effect at lower luminosities and masses. However, others have argued that even the quiescent rates are too high, and proposed significantly lower rates. Fortunately, we can use our recent census of the RSG populations in M31 and M33 to investigate the matter observationally: Higher mass-loss rates will have the effect of reducing the percentage of the highest luminosity RSGs in the luminosity function. We have compared these to the predictions of the Geneva models, including a special set that were run without the enhanced supra-Eddington rates. The observations agree very well with the predictions of the models with the enhanced rates, and rule out lower mass-loss rates.

    This work was partially supported through the National Science Foundation grant AST-1612874, and by NASA through the NASA Hubble Fellowship grant HST-HF2-51516 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555

  59. Bernardinelli, P., Napier, K., Smotherman, H., et al., 2023, AAS, 55, 136.05, First results from the DECam Ecliptic Exploration Project (DEEP)
    The DECam Ecliptic Exploration Project (DEEP) is a survey designed to search for faint (mVR ~ 26.5) trans-Neptunian objects (TNOs) with the Dark Energy Camera (DECam) on the 4 meter Blanco telescope at CTIO. The DEEP fields are distributed along the invariable plane, and the observing strategy is such that TNOs are found in individual nights via digital tracking with a series of exposures in four hour stares, with repeated observations that maximize the recovery potential of these objects in further observing years. We will overview our first results and data release: light curves for objects detected in single exposures (as faint as mVR ~ 24), a precise measurement of the size distribution for the cold Classical Kuiper belt using over 2000 TNO candidates, and over 100 objects with well-determined multi-year orbits. Our survey simulator enables direct comparisons between our observations and models of the trans-Neptunian region, and we reject the CFEPS-L7 model of the Kuiper belt with high significance. Future releases of the DEEP data should double the total number of known TNOs.
  60. Schindler, K., 2023, AAS, 55, 147.02, Clyde Tombaugh's Extraordinary 9-Inch Telescope
    In 1928, Clyde Tombaugh completed construction of his third telescope, a 9-inch reflector. By far his best to date, this one was also noteworthy because of the array of materials from the family farm that he used to build it. The mounting includes parts from a cream separator, automobile axle, and fly wheel from some other piece of equipment, and the tube appears to be a segment of grain auger. The telescope is also an important piece of astronomy history because it was drawings Tombaugh made with this instrument that he sent to Lowell Observatory. Unbeknownst to Tombaugh, his timing was perfect because observatory Director Vesto Slipher was just then looking for an assistant to help with the revived search for a ninth planet that observatory founder Percival Lowell had begun in 1905. Slipher liked the 23-year-old and his work and hired him. Within a year, Tombaugh discovered Pluto. Years later, when Tombaugh relocated to New Mexico, he took the 9-inch with him and continued using it for the rest of his life. In June 2022, Tombaugh's descendants put the telescope up for auction. The philanthropy department at Lowell Observatory put out call to supporters and collected enough pledges to win the auction. The telescope arrived at Lowell Observatory in July and is now on permanent display in the observatory's Rotunda Museum. Staff will also occasionally take it outside at night and use it for viewing, much as Tombaugh did on his Kansas farm nearly a century ago.
  61. Huseby, L., Peacock, S., Carpenter, K., et al., 2023, AAS, 55, 255B.01, The Great Escape! Extreme-UV Spectra Grids for K-Type Stars
    Stellar Extreme Ultraviolet (EUV, 100-1000 A) radiation can influence factors for habitability of planets in K dwarf systems, including driving atmospheric escape and water loss from close-in exoplanets. This wavelength range is currently unobservable due to interstellar contamination and a lack of operational instruments, and so modeling EUV spectra becomes important. We investigated K stars because their atmospheric planetary O 2 and CH 4 spectral features and high planet-star contrast ratio make these systems favorable targets for atmospheric characterization. We modeled the EUV spectra of K stars using the PHOENIX atmospheric code, utilizing Hubble Space Telescope (HST) Far and Near Ultraviolet (FUV, NUV) data for semi-empirical guidance. We categorized each spectral subtype according to temperature and surface gravity and computed the photospheric contribution to each UV flux. Then upper atmosphere models, including chromosphere and transition regions, were computed, added, and compared to HST and Galaxy Evolution Explorer (GALEX) data and adjusted for flux accuracy, including increasing the number of computed non-local thermodynamic equilibrium (non-LTE) species. Strong lines in the FUV and NUV of the synthetic emission spectra that did not match HST data were masked for a more accurate integrated flux calculation. We generated grids of spectra based on the characteristics of K0-K9 stars, which revealed that individualized grids for each spectral subtype will need to be computed, rather than computing one generalized grid applicable for all K dwarf stars. This suite of models will be added to the upcoming PEGASUS (PHOENIX EUV Grid And Stellar UV Spectra) website which will be accessible to the community and searchable using GALEX data. These synthetic spectra involving the EUV can be utilized for studies of star-planet interactions and other simulations involving planet habitability, and will be influential in the identification of potentially habitable planets in K dwarf systems.
  62. Tang, S., Stahl, A., Prato, L., et al., 2023, AAS, 55, 267.13, Searching for the Youngest Hot Jupiters Around T Tauri Stars Tracing Spot Variability Using OH/Fe Line Depth Ratio
    The best way to understand planet formation is to look for planets still forming. Planetary systems that host hot Jupiters are especially intriguing because of hot Jupiters' large sizes and peculiar short orbital periods. Moreover, the formation history of hot Jupiters is vital to the development of habitable worlds. Searching for hot Jupiters around pre-main sequence stars using the radial velocity (RV) method, however, is challenging because of the strong stellar activity of the host star. Large cool spots (as large as 80% of the visible disk) can overwhelm and mimic RV signal induced by planets. The Gaussian Process Regression (GPR) technique has been used widely to isolate the RV signal produced by the stellar activity; however, prior knowledge of the stellar rotation period, and spot(s) lifetime are important for GPR to properly model the activity signal. Knowing these stellar properties is even more critical for applying GPR to young stellar systems where the RV signal from the extreme stellar activity can be several times larger than the planet. Here, we present our preliminary result on a new way to trace spot variability on the stellar surface using the OH/Fe line depth ratio. We will also present a simulation model that can reproduce the observed periodicity of the changes in the OH/Fe line depth ratio. Finally, we will use the hot Jupiters host star, CI Tau, to demonstrate how this new technique can help the community to better find exoplanets around classical T Tauris stars.
  63. O'Grady, A., Drout, M., Gaensler, B., et al., 2023, AAS, 55, 320.04D, Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds: Implications for Thorne-Zytkow Objects and Super-AGB Stars
    The true identity of the peculiar star HV2112, located in the SMC, has been debated. Previous studies have identified it as the first strong Thorne-Zytkow Object (TZO) candidate a class of cool, luminous stars with neutron star cores while others have argued its properties are more consistent with massive or super-AGB (m/sAGB) stars, the latter of which are the most massive stars that do not undergo core collapse supernova. While these studies identified enhanced heavy element abundances in HV2112's atmosphere, it also shows extreme variability (>4 mag), which is abnormal for stars with RSG-like luminosities. We characterized the variability of HV2112 and conducted a systematic search for cool and luminous stars in the Magellanic Clouds with similar variability properties. Using light-curves from ASAS-SN we identified 29 new candidates, nine of which also possess the distinctive light-curve morphology exhibited by HV2112. In this talk we present the results of our analysis of these stars. We find that the temperatures, luminosities, periods, and masses derived from pulsation properties of these sources are consistent with predictions for m/sAGBs, with HV2112 in particular falling into the mass range of the largest sAGBs, and below the theoretical minimum mass for TZOs. Subsequently, we have assessed the presence of heavy elements and lithium in their spectra, and used their local SFH, kinematic, and radio environments to place constraints on the age of progenitor systems and evidence for past supernovae. In all cases results are consistent with an mAGB or sAGB star identity, providing important information on the transition between low and high mass stellar evolution.
  64. Hartman, Z., van Belle, G., Lepine, S., et al., 2023, AAS, 55, 321.02, Initial Results from the Quad-camera Wavefront-sensing Six-channel Speckle Interferometer: Searching for Unresolved Companions in the Widest Low-mass Binaries
    We present initial results of an ongoing speckle imaging campaign at the Lowell Discovery Telescope using the Differential Speckle Survey Instrument (DSSI) and the Quad-camera Wavefront-sensing Six-channel Speckle Interferometer (QWSSI) to search for unresolved third members in low-mass wide binaries. Taking the SUPERWIDE Catalog, we select a sample of low-mass wide binaries with projected physical separations larger than 10,000 au, Gaia G magnitudes brighter than 15.5, and distances less than 100 pc. Using DSSI and QWSSI, we have searched 27 of these systems for unresolved components, achieving an average delta magnitude of about four at 0.1". Combining these results with a previous campaign using NESSI on the WIYN 3.5m Telescope, we find evidence of a lack of close companion detections for low-mass wide binaries when compared with the expectation that most solar-type binaries at these separations should be higher-order multiples. One possibility is that our speckle observations are not probing the entire separation range where possible companions can reside. Given that most solar-type wide binaries at these separations are higher order multiples, we suggest that there are more companions that remain unresolved, and should be detected as spectroscopic binaries. Failure to identify these elusive companions would mean that these systems are true wide binaries and not higher-order multiples.
  65. van Belle, G., von Braun, K., Ciardi, D., et al., 2023, AAS, 55, 341.05, The PTI Giant Star Angular Size Survey: Effective Temperatures & Linear Radii
    We calculate directly determined values for effective temperature (TEFF) and radius (R) for 191 giant stars based upon high resolution angular size measurements from optical interferometry at the Palomar Testbed Interferometer (PTI). Narrow- to wide-band photometry data for the giants are used to establish bolometric fluxes and luminosities through spectral energy distribution fitting, which allow for homogeneously establishing an assessment of spectral type and dereddened V0-K0 color; these two parameters are used as calibration indices for establishing trends in TEFF and R. Spectral types range from G0III to M7.75III, V0-K0 from 1.9 to 8.5. For the V0-K0 = {1.9, 6.5} range, median TEFF uncertainties in the fit of effective temperature versus color are found to be less than 50K; over this range, TEFF drops from 5050K to 3225K. Linear sizes are found to be largely constant at 11 R from G0III to K0III, increasing linearly with subtype to 50 R at K5III, and then further increasing linearly to 150 R by M8III. Three examples of the utility of this data set are presented: first, a fully empirical Hertzsprung-Russell Diagram is constructed and examined against stellar evolution models; second, values for stellar mass are inferred based on measures of R and literature values for log g. Finally, an improved calibration of an angular size prediction tool, based upon V and K values for a star, is presented. These results have been accepted for publication in the Astrophysical Journal.
  66. Archer, H., Hunter, D., Elmegreen, B., et al., 2023, AAS, 55, 361.01, Star Formation and the Role of CO Cores in Dwarf Irregular Galaxy WLM in the Era of JWST
    Dwarf irregular (dIrr) galaxies in the local universe allow us to examine the details of star formation at low metallicity. These low metallicity environments significantly impact molecular cloud formation and structure. Molecular clouds are primarily composed of H2, which is typically traced with low rotational transitions of CO. However, both theory and observation lead us to expect that the structure of the molecular clouds at low metallicities is fundamentally different compared to that found in higher metallicity spirals. Rubio et al. (2015) mapped 10 CO cores in the Local Group dIrr galaxy WLM for the first time at an oxygen abundance 13% of solar. Archer et al. (2022) examined the environments in which these 10 - plus an additional 47 - CO cores formed in WLM and found no obvious characteristics driving the formation of the CO cores. With the spatial resolution and sensitivity offered by the JWST, we can now probe the role in the star-forming regions of resolved CO cores in WLM. In this study, we analyze JWST images of WLM from ERS Program #1334 in the F090W, F150W, F250M, and F430M filters to look for evidence of embedded star formation. We present the first results of a comparison of objects bright in the F250M filter near detected CO cores to those within and away from star forming regions.

    Funding for this work was provided by NSF to D.H. through grant AST-1907492.

  67. Tofflemire, B., Prato, L., Schaefer, G., et al., 2023, AAS, 55, 368.06, Planet Formation in the Binary Environment An ALMA Study of FO Tau
    The majority of Sun-like stars form with binary companions, and their dynamical impact profoundly shapes the formation and survival of their planetary systems. Demographic studies have shown that close binaries (a < 100 au) have suppressed planet-occurrence rates compared to single stars, yet a substantial minority of planets do form and survive at all binary separations. To identify the conditions that foster planet formation in binary systems, we have obtained high-angular-resolution, mm interferometry for a sample of disk-bearing binary systems with known orbital solutions. In this poster, we present the case study of a young binary system, FO Tau (a ~ 22 au). Our ALMA observations resolve dust continuum (1.3 mm) and gas (CO J=2-1) from each circumstellar disk allowing us to trace the dynamical interaction between the binary orbit and the planet-forming reservoir. With these data we determine individual disk orientations and masses, while placing these measurements in the context of a new binary orbital solution. Our findings suggest that the FO Tau system is relatively placid, with observations consistent with alignment between the disks and the binary orbital plane. We compare these findings to models of binary formation and evolution, and their predictions for disk retention and planet formation.
  68. Neugent, K., Massey, P., 2023, AAS, 55, 401.01, Hungry Red Supergiants: Investigating Stellar Mergers in Evolved Massive Stars
    The percentage of massive main-sequence OB stars in binary systems is high, some arguing that it may be as large as 80-100%. However the binary fraction of red supergiants (RSGs) ranges from 15-40%, despite these stars being the evolved descendants of OB stars. One possible explanation for the lack of observed binary RSGs is that many of them have merged. As a binary OB system evolves, the more massive star will leave the main sequence first and evolve into a RSG. If the two stars are close enough, the RSG will expand enough to engulf the secondary, causing a merger as they spin together and gain angular momentum. This event will increase the rotational velocity of the RSG by a measurable amount (> 5 km/s) and lead to unique abundances and physical properties. We've recently observed ~80 Galactic RSGs with EXPRES, a high-resolution spectrograph on the Lowell Discovery Telescope, and are in the process of using this dataset to determine the relative importance of RSG mergers before these stars end their lives as supernovae.

    This work was partially supported by NASA through the NASA Hubble Fellowship grant HST-HF2-51516 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555.

  69. Jackman, J., Shkolnik, E., Million, C., et al., 2023, AAS, 55, 439.05, Bridging The UV Gap: Testing The UV Predictions of Flare Models For M Stars
    Stellar flares are explosive phenomena that release radiation across the entire electromagnetic spectrum. Their far-UV emission can dissociate atmospheric species and exacerbate atmospheric erosion. Yet, the near-UV flux may be necessary for the emergence of life on rocky planets around low-mass stars such as Proxima Centauri, LHS 3384 and TRAPPIST-1. A detailed knowledge of the UV energies and rates of flares is therefore essential for our understanding of the habitability of M dwarf systems. However, measurements of UV flare rates can require expensive campaigns with space-based instruments, limiting such measurements to individual active stars. To get around this, habitability studies instead often use UV rates based on extrapolations from white-light studies with TESS. Despite their use in contemporary habitability studies, such extrapolations are untested and as such their accuracy remains unconstrained. To this end, we are combining TESS optical photometry with archival HST and GALEX spectroscopy and photometry of M dwarfs to test the UV predictions of habitability and exoplanet atmosphere studies. We will show how white-light flare studies underestimate the UV rates of flares, how current models neglect the energy contribution from UV emission lines, and the impact our results have on our current understanding of the UV environments and habitability of terrestrial exoplanets around low-mass stars.
  70. Dorn-Wallenstein, T., Levesque, E., Davenport, J., et al., 2023, AAS, 55, 452.01, The Properties of Fast Yellow Pulsating Supergiants: FYPS Point the Way to Missing Red Supergiants
    Fast yellow pulsating supergiants (FYPS) are a recently-discovered class of evolved massive pulsator. As candidate post-red supergiant objects, and one of the few classes evolved massive pulsators, these objects have incredible potential to change our understanding of the structure and evolution of massive stars. Here we use data from the Transiting Exoplanet Survey Satellite (TESS) in order to examine the distribution of pulsating stars in the upper Hertzprung-Russel (HR) diagram. We find that FYPS occupy a region above logL/L5.0, corresponding to stars with initial masses 18-20 M, consistent with the most massive red supergiant progenitors of supernovae (SNe) II-P, as well as the observed properties of SNe IIb progenitors. This threshold is in agreement with the picture that FYPS are post-RSG stars. The observed properties of FYPS make them fascinating objects for future theoretical study.
  71. Omori, Y., Baxter, E., Chang, C., et al., 2023, PhRvD, 107, 023529, Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck. I. Construction of CMB lensing maps and modeling choices
    Joint analyses of cross-correlations between measurements of galaxy positions, galaxy lensing, and lensing of the cosmic microwave background (CMB) offer powerful constraints on the large-scale structure of the Universe. In a forthcoming analysis, we will present cosmological constraints from the analysis of such cross-correlations measured using Year 3 data from the Dark Energy Survey (DES), and CMB data from the South Pole Telescope (SPT) and Planck. Here we present two key ingredients of this analysis: (1) an improved CMB lensing map in the SPT-SZ survey footprint and (2) the analysis methodology that will be used to extract cosmological information from the cross-correlation measurements. Relative to previous lensing maps made from the same CMB observations, we have implemented techniques to remove contamination from the thermal Sunyaev Zel'dovich effect, enabling the extraction of cosmological information from smaller angular scales of the cross-correlation measurements than in previous analyses with DES Year 1 data. We describe our model for the cross-correlations between these maps and DES data, and validate our modeling choices to demonstrate the robustness of our analysis. We then forecast the expected cosmological constraints from the galaxy survey-CMB lensing auto and cross-correlations. We find that the galaxy-CMB lensing and galaxy shear-CMB lensing correlations will on their own provide a constraint on S8=8{m/0.3 } at the few percent level, providing a powerful consistency check for the DES-only constraints. We explore scenarios where external priors on shear calibration are removed, finding that the joint analysis of CMB lensing cross-correlations can provide constraints on the shear calibration amplitude at the 5% to 10% level.
  72. Chang, C., Omori, Y., Baxter, E., et al., 2023, PhRvD, 107, 023530, Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and P l a n c k . II. Cross-correlation measurements and cosmological constraints
    Cross-correlations of galaxy positions and galaxy shears with maps of gravitational lensing of the cosmic microwave background (CMB) are sensitive to the distribution of large-scale structure in the Universe. Such cross-correlations are also expected to be immune to some of the systematic effects that complicate correlation measurements internal to galaxy surveys. We present measurements and modeling of the cross-correlations between galaxy positions and galaxy lensing measured in the first three years of data from the Dark Energy Survey with CMB lensing maps derived from a combination of data from the 2500 deg2 SPT-SZ survey conducted with the South Pole Telescope and full-sky data from the Planck satellite. The CMB lensing maps used in this analysis have been constructed in a way that minimizes biases from the thermal Sunyaev Zel'dovich effect, making them well suited for cross-correlation studies. The total signal-to-noise of the cross-correlation measurements is 23.9 (25.7) when using a choice of angular scales optimized for a linear (nonlinear) galaxy bias model. We use the cross-correlation measurements to obtain constraints on cosmological parameters. For our fiducial galaxy sample, which consist of four bins of magnitude-selected galaxies, we find constraints of m=0.272-0.052+0.032 and S88{m/0.3 }=0.736-0.028+0.032 (m=0.245-0.044+0.026 and S8=0.734-0.028+0.035 ) when assuming linear (nonlinear) galaxy bias in our modeling. Considering only the cross-correlation of galaxy shear with CMB lensing, we find m=0.270-0.061+0.043 and S8=0.740-0.029+0.034 . Our constraints on S8 are consistent with recent cosmic shear measurements, but lower than the values preferred by primary CMB measurements from Planck.
  73. Abbott, T., Aguena, M., Alarcon, A., et al., 2023, PhRvD, 107, 023531, Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck. III. Combined cosmological constraints
    We present cosmological constraints from the analysis of two-point correlation functions between galaxy positions and galaxy lensing measured in Dark Energy Survey (DES) Year 3 data and measurements of cosmic microwave background (CMB) lensing from the South Pole Telescope (SPT) and Planck. When jointly analyzing the DES-only two-point functions and the DES cross-correlations with SPT +P l a n c k CMB lensing, we find m=0.344 0.030 and S88(m/0.3 )0.5=0.773 0.016 , assuming CDM . When additionally combining with measurements of the CMB lensing autospectrum, we find m=0.306-0.021+0.018 and S8=0.792 0.012 . The high signal-to-noise of the CMB lensing cross-correlations enables several powerful consistency tests of these results, including comparisons with constraints derived from cross-correlations only, and comparisons designed to test the robustness of the galaxy lensing and clustering measurements from DES. Applying these tests to our measurements, we find no evidence of significant biases in the baseline cosmological constraints from the DES-only analyses or from the joint analyses with CMB lensing cross-correlations. However, the CMB lensing cross-correlations suggest possible problems with the correlation function measurements using alternative lens galaxy samples, in particular the REDMAGIC galaxies and high-redshift MAGLIM galaxies, consistent with the findings of previous studies. We use the CMB lensing cross-correlations to identify directions for further investigating these problems.
  74. O'Grady, A., Drout, M., Gaensler, B., et al., 2023, ApJ, 943, 18, Cool, Luminous, and Highly Variable Stars in the Magellanic Clouds. II. Spectroscopic and Environmental Analysis of Thorne-Zytkow Object and Super-AGB Star Candidates
    In previous work, we identified a population of 38 cool and luminous variable stars in the Magellanic Clouds and examined 11 in detail in order to classify them as either Thorne-Zytkow objects (TZOs; red supergiants with a neutron star cores) or super-asymptotic giant branch (sAGB) stars (the most massive stars that will not undergo core collapse). This population includes HV 2112, a peculiar star previously considered in other works to be either a TZO or high-mass asymptotic giant branch (AGB) star. Here we continue this investigation, using the kinematic and radio environments and local star formation history of these stars to place constraints on the age of the progenitor systems and the presence of past supernovae. These stars are not associated with regions of recent star formation, and we find no evidence of past supernovae at their locations. Finally, we also assess the presence of heavy elements and lithium in their spectra compared to red supergiants. We find strong absorption in Li and s-process elements compared to RSGs in most of the sample, consistent with sAGB nucleosynthesis, while HV 2112 shows additional strong lines associated with TZO nucleosynthesis. Coupled with our previous mass estimates, the results are consistent with the stars being massive (~4-6.5 M ) or sAGB (~6.5-12 M ) stars in the thermally pulsing phase, providing crucial observations of the transition between low- and high-mass stellar populations. HV 2112 is more ambiguous; it could either be a maximally massive sAGB star, or a TZO if the minimum mass for stability extends down to 13 M .
  75. Morgan, R., Nord, B., Bechtol, K., et al., 2023, ApJ, 943, 19, DeepZipper. II. Searching for Lensed Supernovae in Dark Energy Survey Data with Deep Learning
    Gravitationally lensed supernovae (LSNe) are important probes of cosmic expansion, but they remain rare and difficult to find. Current cosmic surveys likely contain 5-10 LSNe in total while next-generation experiments are expected to contain several hundred to a few thousand of these systems. We search for these systems in observed Dark Energy Survey (DES) five year SN fields-10 3 sq. deg. regions of sky imaged in the griz bands approximately every six nights over five years. To perform the search, we utilize the DeepZipper approach: a multi-branch deep learning architecture trained on image-level simulations of LSNe that simultaneously learns spatial and temporal relationships from time series of images. We find that our method obtains an LSN recall of 61.13% and a false-positive rate of 0.02% on the DES SN field data. DeepZipper selected 2245 candidates from a magnitude-limited (m i < 22.5) catalog of 3,459,186 systems. We employ human visual inspection to review systems selected by the network and find three candidate LSNe in the DES SN fields.
  76. Lopez-Valdivia, R., Mace, G., Han, E., et al., 2023, ApJ, 943, 49, The IGRINS YSO Survey. III. Stellar Parameters of Pre-main-sequence Stars in Ophiuchus and Upper Scorpius
    We used the Immersion GRating Infrared Spectrometer (IGRINS) to determine fundamental parameters for 61 K- and M-type young stellar objects (YSOs) located in the Ophiuchus and Upper Scorpius star-forming regions. We employed synthetic spectra and a Markov chain Monte Carlo approach to fit specific K-band spectral regions and determine the photospheric temperature (T), surface gravity ( $\mathrm{log}g$ ), magnetic field strength (B), projected rotational velocity ( $v\sin i$ ), and K-band veiling (r K ). We determined B for ~46% of our sample. Stellar parameters were compared to the results from Taurus-Auriga and the TW Hydrae association presented in Paper I of this series. We classified all the YSOs in the IGRINS survey with infrared spectral indices from Two Micron All Sky Survey and Wide-field Infrared Survey Explorer photometry between 2 and 24 m. We found that Class II YSOs typically have lower $\mathrm{log}g$ and $v\sin i$ , similar B, and higher K-band veiling than their Class III counterparts. Additionally, we determined the stellar parameters for a sample of K and M field stars also observed with IGRINS. We have identified intrinsic similarities and differences at different evolutionary stages with our homogeneous determination of stellar parameters in the IGRINS YSO survey. Considering $\mathrm{log}g$ as a proxy for age, we found that the Ophiuchus and Taurus samples have a similar age. We also find that Upper Scorpius and TWA YSOs have similar ages, and are more evolved than Ophiuchus/Taurus YSOs.
  77. Massey, P., Neugent, K., Ekstrom, S., et al., 2023, ApJ, 942, 69, The Time-averaged Mass-loss Rates of Red Supergiants as Revealed by Their Luminosity Functions in M31 and M33
    Mass loss in red supergiants (RSGs) is generally recognized to be episodic, but mass-loss prescriptions fail to reflect this. Evolutionary models show that the total amount of mass lost in this phase determines if these stars evolve to warmer temperatures before undergoing core collapse. The current Geneva evolutionary models mimic episodic mass loss by enhancing the quiescent prescription rates whenever the star's outer layers exceed the Eddington luminosity by a large factor. This results in a 20 M model undergoing 10 more mass loss than it would otherwise, but has little effect on models of lower mass. We can test the validity of this approach observationally by measuring the proportion of high-luminosity RSGs to that predicted by the models. To do this, we use our recent luminosity-limited census of RSGs in M31 and M33, making modest improvements to membership, and adopting extinctions based on the recent panchromatic M31 and M33 Hubble surveys. We then compare the proportions of the highest luminosity RSGs found to that predicted by published Geneva models, as well as to a special set of models computed without the enhanced rates. We find good agreement with the models which include the supra-Eddington enhanced mass loss. The models with lower mass-loss rates predict a larger fraction of high-luminosity RSGs than observed, and thus can be ruled out. We also use these improved data to confirm that the upper luminosity limit of RSGs is $\mathrm{log}L/{L}_{\odot }\sim 5.4$ , regardless of metallicity, using our improved data on M31 and M33 plus previous results on the Magellanic Clouds.
  78. Margon, B., Morrell, N., Massey, P., et al., 2023, ApJ, 942, 85, A Survey for C II Emission-line Stars in the Large Magellanic Cloud. II. Final Results and the Origin of C II Emission in [WC] Spectra
    We present the final results of an imaging and spectroscopic search for stars in the Large Magellanic Cloud (LMC) with C II 7231, 7236 emission lines. The goal is to identify and study [WC11] stars, the coolest of the low-mass Wolf-Rayet sequence, and a subset of central stars of planetary nebulae where the C II lines are known to be especially prominent. A recent serendipitous discovery of an LMC [WC11] raised the possibility that these objects, although difficult to identify, might in fact be more common than previously believed. Several new members of this rare class have been found in this survey. It now seems clear, however, that a significant number of these stars are not hiding among the general [WC] population. We point out that the C II doublet intensity ratio observed in our spectra proves to neatly divide the objects into two distinct groups, with the C II emission likely originating from either the stellar wind or a surrounding nebula. The physics of the C II emission mechanism correctly explains this bifurcation. Spectral subtypes are suggested for most of the objects. The numerous spectroscopic clues now available for these objects should facilitate future detailed modeling.
  79. Meldorf, C., Palmese, A., Brout, D., et al., 2023, MNRAS, 518, 1985, The Dark Energy Survey Supernova Program results: type Ia supernova brightness correlates with host galaxy dust
    Cosmological analyses with type Ia supernovae (SNe Ia) often assume a single empirical relation between colour and luminosity () and do not account for varying host-galaxy dust properties. However, from studies of dust in large samples of galaxies, it is known that dust attenuation can vary significantly. Here, we take advantage of state-of-the-art modelling of galaxy properties to characterize dust parameters (dust attenuation AV, and a parameter describing the dust law slope RV) for 1100 Dark Energy Survey (DES) SN host galaxies. Utilizing optical and infrared data of the hosts alone, we find three key aspects of host dust that impact SN cosmology: (1) there exists a large range (~1-6) of host RV; (2) high-stellar mass hosts have RV on average ~0.7 lower than that of low-mass hosts; (3) for a subsample of 81 spectroscopically classified SNe there is a significant (>3) correlation between the Hubble diagram residuals of red SNe Ia and the host RV that when corrected for reduces scatter by $\sim 13{{\ \rm per\ cent}}$ and the significance of the 'mass step' to ~1. These represent independent confirmations of recent predictions based on dust that attempted to explain the puzzling 'mass step' and intrinsic scatter (int) in SN Ia analyses.
  80. Cheng, T., Dominguez Sanchez, H., Vega-Ferrero, J., et al., 2023, MNRAS, 518, 2794, Lessons learned from the two largest Galaxy morphological classification catalogues built by convolutional neural networks
    We compare the two largest galaxy morphology catalogues, which separate early- and late-type galaxies at intermediate redshift. The two catalogues were built by applying supervised deep learning (convolutional neural networks, CNNs) to the Dark Energy Survey data down to a magnitude limit of ~21 mag. The methodologies used for the construction of the catalogues include differences such as the cutout sizes, the labels used for training, and the input to the CNN - monochromatic images versus gri-band normalized images. In addition, one catalogue is trained using bright galaxies observed with DES (i < 18), while the other is trained with bright galaxies (r < 17.5) and 'emulated' galaxies up to r-band magnitude 22.5. Despite the different approaches, the agreement between the two catalogues is excellent up to i < 19, demonstrating that CNN predictions are reliable for samples at least one magnitude fainter than the training sample limit. It also shows that morphological classifications based on monochromatic images are comparable to those based on gri-band images, at least in the bright regime. At fainter magnitudes, i > 19, the overall agreement is good (~95 per cent), but is mostly driven by the large spiral fraction in the two catalogues. In contrast, the agreement within the elliptical population is not as good, especially at faint magnitudes. By studying the mismatched cases, we are able to identify lenticular galaxies (at least up to i < 19), which are difficult to distinguish using standard classification approaches. The synergy of both catalogues provides an unique opportunity to select a population of unusual galaxies.
  81. Vincenzi, M., Sullivan, M., Moller, A., et al., 2023, MNRAS, 518, 1106, The Dark Energy Survey supernova program: cosmological biases from supernova photometric classification
    Cosmological analyses of samples of photometrically identified type Ia supernovae (SNe Ia) depend on understanding the effects of 'contamination' from core-collapse and peculiar SN Ia events. We employ a rigorous analysis using the photometric classifier SuperNNova on state-of-the-art simulations of SN samples to determine cosmological biases due to such 'non-Ia' contamination in the Dark Energy Survey (DES) 5-yr SN sample. Depending on the non-Ia SN models used in the SuperNNova training and testing samples, contamination ranges from 0.8 to 3.5 per cent, with a classification efficiency of 97.7-99.5 per cent. Using the Bayesian Estimation Applied to Multiple Species (BEAMS) framework and its extension BBC ('BEAMS with Bias Correction'), we produce a redshift-binned Hubble diagram marginalized over contamination and corrected for selection effects, and use it to constrain the dark energy equation-of-state, w. Assuming a flat universe with Gaussian M prior of 0.311 0.010, we show that biases on w are <0.008 when using SuperNNova, with systematic uncertainties associated with contamination around 10 per cent of the statistical uncertainty on w for the DES-SN sample. An alternative approach of discarding contaminants using outlier rejection techniques (e.g. Chauvenet's criterion) in place of SuperNNova leads to biases on w that are larger but still modest (0.015-0.03). Finally, we measure biases due to contamination on w0 and wa (assuming a flat universe), and find these to be <0.009 in w0 and <0.108 in wa, 5 to 10 times smaller than the statistical uncertainties for the DES-SN sample.
  82. Schmidt, T., Treu, T., Birrer, S., et al., 2023, MNRAS, 518, 1260, STRIDES: automated uniform models for 30 quadruply imaged quasars
    Gravitational time delays provide a powerful one-step measurement of H0, independent of all other probes. One key ingredient in time-delay cosmography are high-accuracy lens models. Those are currently expensive to obtain, both, in terms of computing and investigator time (105-106 CPU hours and ~0.5-1 yr, respectively). Major improvements in modelling speed are therefore necessary to exploit the large number of lenses that are forecast to be discovered over the current decade. In order to bypass this roadblock, we develop an automated modelling pipeline and apply it to a sample of 31 lens systems, observed by the Hubble Space Telescope in multiple bands. Our automated pipeline can derive models for 30/31 lenses with few hours of human time and <100 CPU hours of computing time for a typical system. For each lens, we provide measurements of key parameters and predictions of magnification as well as time delays for the multiple images. We characterize the cosmography-readiness of our models using the stability of differences in the Fermat potential (proportional to time delay) with respect to modelling choices. We find that for 10/30 lenses, our models are cosmography or nearly cosmography grade (<3 per cent and 3-5 per cent variations). For 6/30 lenses, the models are close to cosmography grade (5-10 per cent). These results utilize informative priors and will need to be confirmed by further analysis. However, they are also likely to improve by extending the pipeline modelling sequence and options. In conclusion, we show that uniform cosmography grade modelling of large strong lens samples is within reach.
  83. Amon, A., Robertson, N., Miyatake, H., et al., 2023, MNRAS, 518, 477, Consistent lensing and clustering in a low-S8 Universe with BOSS, DES Year 3, HSC Year 1, and KiDS-1000
    We evaluate the consistency between lensing and clustering based on measurements from Baryon Oscillation Spectroscopic Survey combined with galaxy-galaxy lensing from Dark Energy Survey (DES) Year 3, Hyper Suprime-Cam Subaru Strategic Program (HSC) Year 1, and Kilo-Degree Survey (KiDS)-1000. We find good agreement between these lensing data sets. We model the observations using the DARK EMULATOR and fit the data at two fixed cosmologies: Planck (S8 = 0.83), and a Lensing cosmology (S8 = 0.76). For a joint analysis limited to large scales, we find that both cosmologies provide an acceptable fit to the data. Full utilization of the higher signal-to-noise small-scale measurements is hindered by uncertainty in the impact of baryon feedback and assembly bias, which we account for with a reasoned theoretical error budget. We incorporate a systematic inconsistency parameter for each redshift bin, A, that decouples the lensing and clustering. With a wide range of scales, we find different results for the consistency between the two cosmologies. Limiting the analysis to the bins for which the impact of the lens sample selection is expected to be minimal, for the Lensing cosmology, the measurements are consistent with A = 1; A = 0.91 0.04 (A = 0.97 0.06) using DES+KiDS (HSC). For the Planck case, we find a discrepancy: A = 0.79 0.03 (A = 0.84 0.05) using DES+KiDS (HSC). We demonstrate that a kinematic Sunyaev-Zeldovich-based estimate for baryonic effects alleviates some of the discrepancy in the Planck cosmology. This analysis demonstrates the statistical power of small-scale measurements; however, caution is still warranted given modelling uncertainties and foreground sample selection effects.
  84. Fitzmaurice, E., Martin, D., Rodriguez Martinez, R., et al., 2023, MNRAS, 518, 636, Spectroscopy of TOI-1259B - an unpolluted white dwarf companion to an inflated warm Saturn
    TOI-1259 consists of a transiting exoplanet orbiting a main-sequence star, with a bound outer white dwarf (WDs) companion. Less than a dozen systems with this architecture are known. We conduct follow-up spectroscopy on the WD TOI-1259B using the Large Binocular Telescope to better characterize it. We observe only strong hydrogen lines, making TOI-1259B a DA WD. We see no evidence of heavy element pollution, which would have been evidence of planetary material around the WD. Such pollution is seen in $\sim 25{-}50{{\ \rm per\ cent}}$ of WDs, but it is unknown if this rate is higher or lower in TOI-1259-like systems that contain a known planet. Our spectroscopy permits an improved WD age measurement of $4.05^{+1.00}_{-0.42}$ Gyr, which matches gyrochronology of the main-sequence star. This is the first of an expanded sample of similar binaries that will allow us to calibrate these dating methods and provide a new perspective on planets in binaries.
  85. del Ser, D., Fors, O., del Alcazar, M., et al., 2023, MNRAS, 518, 669, TFAW survey II: six newly validated planets and 13 planet candidates from K2
    Searching for Earth-sized planets in data from Kepler's extended mission (K2) is a niche that still remains to be fully exploited. The TFAW survey is an ongoing project that aims to re-analyse all light curves in K2 C1-C8 and C12-C18 campaigns with a wavelet-based detrending and denoising method, and the period search algorithm TLS to search for new transit candidates not detected in previous works. We have analysed a first subset of 24 candidate planetary systems around relatively faint host stars (10.9 < Kp < 15.4) to allow for follow-up speckle imaging observations. Using vespa and TRICERATOPS, we statistically validate six candidates orbiting four unique host stars by obtaining false-positive probabilities smaller than 1 per cent with both methods. We also present 13 vetted planet candidates that might benefit from other, more precise follow-up observations. All of these planets are sub-Neptune-sized with two validated planets and three candidates with sub-Earth sizes, and have orbital periods between 0.81 and 23.98 d. Some interesting systems include two ultra-short-period planets, three multiplanetary systems, three sub-Neptunes that appear to be within the small planet Radius Gap, and two validated and one candidate sub-Earths (EPIC 210706310.01, K2-411 b, and K2-413 b) orbiting metal-poor stars.
  86. Lilleengen, S., Petersen, M., Erkal, D., et al., 2023, MNRAS, 518, 774, The effect of the deforming dark matter haloes of the Milky Way and the Large Magellanic Cloud on the Orphan-Chenab stream
    It has recently been shown that the Large Magellanic Cloud (LMC) has a substantial effect on the Milky Way's stellar halo and stellar streams. Here, we explore how deformations of the Milky Way and LMC's dark matter haloes affect stellar streams, and whether these effects are observable. In particular, we focus on the Orphan-Chenab (OC) stream which passes particularly close to the LMC and spans a large portion of the Milky Way's halo. We represent the Milky Way-LMC system using basis function expansions that capture their evolution in an N-body simulation. We present the properties of this system, such as the evolution of the densities and force fields of each galaxy. The OC stream is evolved in this time-dependent, deforming potential, and we investigate the effects of the various moments of the Milky Way and the LMC. We find that the simulated OC stream is strongly influenced by the deformations of both the Milky Way and the LMC and that this effect is much larger than current observational errors. In particular, the Milky Way dipole has the biggest impact on the stream, followed by the evolution of the LMC's monopole, and the LMC's quadrupole. Detecting these effects would confirm a key prediction of collisionless, cold dark matter, and would be a powerful test of alternative dark matter and alternative gravity models.
  87. Cook, J., Protopapa, S., Dalle Ore, C., et al., 2023, Icar, 389, 115242, Analysis of Charon's spectrum at 2.21- m from New Horizons/LEISA and Earth-based observations
    We examine the 2.21- m band from 19 disk-integrated Charon spectra measured by New Horizons/LEISA in the week leading up to its closest encounter with the Pluto system. These observations cover one Charon rotation period. Additionally, we analyze Charon's 2.21- m band from 22 Earth-based spectra obtained over the last two decades. We measure the equivalent width of the 2.21- m band from all observations and study it as a function of sub-observer longitude. We find no significant variation in the 2.21- m band as Charon rotates. Compared to the same band seen on Nix and Hydra, Charon's 2.21- m band is several times weaker. We attribute the 2.21- m band to NH4Cl based on the appearance of a weaker band at 2.24- m . Furthermore, we see two never-before-reported absorption features in Charon's spectrum at 1.60 and 1.63- m , which may also be due to NH4Cl. If NH3-H2O-ice mixtures are present on Charon, they must be a small fraction of the disk-average composition to be consistent with the spectrum at 1.99- m .
  88. DeMeo, F., Marsset, M., Polishook, D., et al., 2023, Icar, 389, 115264, Isolating the mechanisms for asteroid surface refreshing
    Evidence is seen for young, fresh surfaces among Near-Earth and Main-Belt asteroids even though space-weathering timescales are shorter than the age of the surfaces. A number of mechanisms have been proposed to refresh asteroid surfaces on short timescales, such as planetary encounters, YORP spinup, thermal degradation, and collisions. Additionally, other factors such as grain size effects have been proposed to explain the existence of these "fresh-looking" spectra. To investigate the role each of these mechanisms may play, we collected a sample of visible and near-infrared spectra of 477 near-Earth and Mars Crosser asteroids with similar sizes and compositions - all with absolute magnitude H > 16 and within the S-complex and having olivine to pyroxene (ol/(ol+opx)) ratios >0.65. We taxonomically classify these objects in the Q (fresh) and S (weathered) classes. We find four trends in the Q/S ratio: (1) previous work demonstrated the Q/S ratio increases at smaller sizes down to H 16, but we find a sharp increase near H 19 after which the ratio decreases monotonically. (2) in agreement with many previous studies, the Q/S ratio increases with decreasing perihelion distance, and we find it is non-zero for larger perihelia >1.2AU, (3) as a new finding our work reveals the Q/S ratio has a sharp, significant peak near 5 orbital inclination, and (4) we confirm previous findings that the Q/S ratio is higher for objects that have the possibility of encounter with Earth and Venus versus those that do not, however this finding cannot be distinguished from the perihelion trend. No single resurfacing mechanism can explain all of these trends, so multiple mechanisms are required. YORP spin-up scales with size, thermal degradation is dependent on perihelion, planetary encounters trend with inclination, perihelion and MOID, noting that asteroid-asteroid collisions are also dependent on inclination. It is likely that a combination of all four resurfacing mechanisms are needed to account for all observational trends.
  89. 88 publications and 284 citations in 2023.

88 publications and 284 citations total.