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Research involving Lowell Observatory staff 2024
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This is a work ever in progress.

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    2024

  1. Jenniskens, P., Pilorz, S., Gural, P., et al., (including Avner, D., Blomquist, S., Gialluca, M., Hemmelgarn, S., Moskovitz, N.), 2024, Icar, 415, 116034, Lifetime of cm-sized zodiacal dust from the physical and dynamical evolution of meteoroid streams
    While comets eject mass mostly at cm-sizes and larger, that size range of particles is mostly absent from the interplanetary medium. Such particles are thought to be lost from the solar system by grain-grain collisions. Here, we investigate the lifetime of cm-sized meteoroids from their abundance in meteoroid streams of different age. For 487 streams, we measured the orbital element dispersions, the magnitude size distribution index, the ratio of fluffy and dense materials in the stream and their bulk densities, and the meteor light curve shape-parameter. We find that older long-period comet meteoroid streams tend to be more dispersed and evolve towards smaller semi-major axis, higher magnitude size distribution index, and contain relatively more high-density material. Meteoroids that approach the Sun closer than 0.2-0.3 AU are mostly young and composed of denser materials poor in sodium. We compare the observed properties of the streams to age estimates from the literature and to a set of new age estimates for long-period comet streams based on observed dispersions. We find that streams broaden with age inversely proportional to the perihelion distance (q). By selecting narrow ranges of age, we find that their magnitude distribution index changes proportional to 1/q, less steep than expected from meteoroid destruction by collisions. Instead, this shallow dependence suggests a lifetime inversely proportional to the peak grain temperature along its orbit, with the lifetime limited by thermal stresses if 0.3 < q < 1.02 AU and by sublimation if q < 0.2 AU.
  2. Eisner, N., Grunblatt, S., Barragan, O., et al., (including Llama, J.), 2024, AJ, 167, 241, Planet Hunters TESS. V. A Planetary System Around a Binary Star, Including a Mini-Neptune in the Habitable Zone
    We report on the discovery and validation of a transiting long-period mini-Neptune orbiting a bright (V = 9.0 mag) G dwarf (TOI 4633; R = 1.05 R , M = 1.10 M ). The planet was identified in data from the Transiting Exoplanet Survey Satellite by citizen scientists taking part in the Planet Hunters TESS project. Modelling of the transit events yields an orbital period of 271.9445 0.0040 days and radius of 3.2 0.20 R . The Earth-like orbital period and an incident flux of ${1.56}_{-0.16}^{+0.20}$ F places it in the optimistic habitable zone around the star. Doppler spectroscopy of the system allowed us to place an upper mass limit on the transiting planet and revealed a non-transiting planet candidate in the system with a period of 34.15 0.15 days. Furthermore, the combination of archival data dating back to 1905 with new high angular resolution imaging revealed a stellar companion orbiting the primary star with an orbital period of around 230 yr and an eccentricity of about 0.9. The long period of the transiting planet, combined with the high eccentricity and close approach of the companion star makes this a valuable system for testing the formation and stability of planets in binary systems.
  3. Tofflemire, B., Prato, L., Kraus, A., et al., 2024, AJ, 167, 232, Sites of Planet Formation in Binary Systems. I. Evidence for DiskOrbit Alignment in the Close Binary FO Tau
    Close binary systems present challenges to planet formation. As binary separations decrease, so do the occurrence rates of protoplanetary disks in young systems and planets in mature systems. For systems that do retain disks, their disk masses and sizes are altered by the presence of the binary companion. Through the study of protoplanetary disks in binary systems with known orbital parameters, we seek to determine the properties that promote disk retention and therefore planet formation. In this work, we characterize the young binarydisk system FO Tau. We determine the first full orbital solution for the system, finding masses of ${0.35}_{-0.05}^{+0.06}\ {M}_{\odot }$ and 0.34 0.05 M for the stellar components, a semimajor axis of $22{\,(}_{-1}^{+2})$ au, and an eccentricity of $0.21{\,(}_{-0.03}^{+0.04})$ . With long-baseline Atacama Large Millimeter/submillimeter Array interferometry, we detect 1.3 mm continuum and 12CO (J = 21) line emission toward each of the binary components; no circumbinary emission is detected. The protoplanetary disks are compact, consistent with being truncated by the binary orbit. The dust disks are unresolved in the image plane, and the more extended gas disks are only marginally resolved. Fitting the continuum and CO visibilities, we determine the inclination of each disk, finding evidence for alignment of the disk and binary orbital planes. This study is the first of its kind linking the properties of circumstellar protoplanetary disks to a precisely known binary orbit. In the case of FO Tau, we find a dynamically placid environment (coplanar, low eccentricity), which may foster its potential for planet formation.
  4. Goksu, O., Kutra, T., Wu, Y., 2024, AJ, 167, 236, On the Rigidly Precessing, Eccentric Gas Disk Orbiting the White Dwarf SDSS J1228+1040
    Metal pollution onto white dwarfs is a widespread phenomenon that remains puzzling. Some of these white dwarfs also harbor gaseous debris disks. Emission lines from these disks open a unique window to the physical properties of the polluting material, lending insights into their origin. We model the emission line kinematics for the gas disk around SDSS J1228+1040, a system that has been monitored for over two decades. We show that the disk mass is strongly peaked at 1 R (modulo the unknown inclination), and the disk eccentricity decreases from a value of 0.44 at the inner edge, to nearly zero at the outer edge. This eccentricity profile is exactly what one expects if the disk is in a global eccentric mode, precessing rigidly under general relativity and gas pressure. The precession period is about two decades. We infer that the mass of the gas disk is roughly equivalent to that of a 50 km rocky body, while the mass of the accompanying dust disk is likely insignificant. The disk eccentricity confirms an origin in tidal disruption, while the short disk diffusion time suggests that the disruption event happened a few centuries ago. Moreover, we argue that the initial orbit for the disrupted body, and that of its putative planetary perturber, fall within an astronomical unit around the white dwarf. The total mass of the source population is likely orders of magnitude more massive than our own Asteroid belt and does not seem to exist around main-sequence stars.
  5. Hasegawa, S., Marsset, M., DeMeo, F., et al., (including Burt, B.), 2024, AJ, 167, 224, Candidate Main-belt Asteroids for Surface Heterogeneity
    Large terrestrial bodies in our solar system like the Earth, Mars, Mercury, and the Moon exhibit geologically complex surfaces with compositional heterogeneity. From past studies using large telescopes and spacecraft, it was shown that asteroids with diameters larger than 100 km also show surface heterogeneity at hemispheric scales, while on smaller objects, such features remain to be detected. Here, we investigate candidates for surface heterogeneity in a sample of 130 main-belt asteroids using multiepoch spectroscopic data from the MITHawaii Near-Earth Object Spectroscopic Survey, which has been observing asteroids for about 20 yr using a self-consistent observation technique. Twelve conservative candidates with spectra more than 3 apart from each other at 2.4 m and 52 optimistic candidates for surface heterogeneity are detected. These candidates include eight objects already reported as being heterogeneous. Our study suggests that the size boundary between small homogeneous asteroids and larger heterogeneous objects, if it exists, is lower than 100 km. A-type asteroids have a higher proportion of heterogeneous candidates than other asteroids. This may be because olivine, which is the main surface constituent of these objects, reacts more efficiently to space weathering with respect to pyroxene, such that a similar range of surface ages will translate into a wider range of optical-to-near-infrared spectral slopes in the case of A-type bodies.
  6. Blakley, B., Grundy, W., Steckloff, J., et al., (including Hanley, J., Koga, K.), 2024, P&SS, 244, 105863, The equilibrium vapor pressures of ammonia and oxygen ices at outer solar system temperatures
    Few laboratory studies have investigated the vapor pressures of the volatiles that may be present as ices in the outer solar system; even fewer studies have investigated these species at the temperatures and pressures suitable to the surfaces of icy bodies in the Saturnian and Uranian systems (<100 K, <10-9 bar). This study adds to the work of Grundy et al. (2024) in extending the known equilibrium vapor pressures of outer solar system ices through laboratory investigations at very low temperatures. Our experiments with ammonia and oxygen ices provide new thermodynamic models for these species' respective enthalpies of sublimation. We find that ammonia ice, and to a lesser degree oxygen ice, are stable at higher temperatures than extrapolations in previous literature have predicted. Our results show that these ices should be retained over longer periods of time than previous extrapolations would predict, and a greater amount of these solids is required to support observation in exospheres of airless bodies in the outer solar system.
  7. Emery, J., Wong, I., Brunetto, R., et al., (including Grundy, W.), 2024, Icar, 414, 116017, A tale of 3 dwarf planets: Ices and organics on Sedna, Gonggong, and Quaoar from JWST spectroscopy
    The dwarf planets Sedna, Gonggong, and Quaoar are interesting in being somewhat smaller than the methane-rich bodies of the Kuiper Belt (Pluto, Eris, Makemake), yet large enough to be spherical and to have possibly undergone interior melting and differentiation. They also reside on very different orbits, making them an ideal suite of bodies for untangling effects of size and orbit on present day surface composition. We observed Sedna, Gonggong, and Quaoar with the NIRSpec instrument on the James Webb Space Telescope (JWST). All three bodies were observed in the low-resolution prism mode at wavelengths spanning 0.7 to 5.2 m. Quaoar was additionally observed at 10 higher spectral resolution from 0.97 to 3.16 m using medium-resolution gratings. Sedna's spectrum shows a large number of absorption features due to ethane (C2H6), as well as acetylene (C2H2), ethylene (C2H4), H2O, and possibly CO2. Gonggong's spectrum also shows several, but fewer and weaker, ethane features, along with stronger and cleaner H2O features and CO2 complexed with other molecules. Quaoar's prism spectrum shows even fewer and weaker ethane features, the deepest and cleanest H2O features, a feature at 3.2 m possibly due to HCN, and CO2 ice. The higher-resolution medium grating spectrum of Quaoar reveals several overtone and combination bands of ethane and methane (CH4). Spectra of all three objects show steep red spectral slopes and strong, broad absorptions between 2.7 and 3.6 m indicative of complex organic molecules. The suite of light hydrocarbons and complex organic molecules are interpreted as the products of irradiation of methane. We infer that the differences in apparent abundances of irradiation products among these three similarly-sized bodies are likely due to their distinctive orbits, which lead to different timescales of methane retention and to different charged particle irradiation environments. In all cases, however, the continued presence of light hydrocarbons implies a resupply of methane to the surface. We suggest that these three bodies have undergone internal melting and geochemical evolution similar to the larger dwarf planets and distinct from all smaller KBOs. The feature identification presented in this paper is the first step of analysis, and additional insight into the relative abundances and mixing states of materials on these surfaces will come from future spectral modeling of these data.
  8. Knieling, B., Schindler, K., Sickafoose, A., et al., (including Levine, S.), 2024, PSJ, 5, 104, Stellar Occultations in the Era of Data Mining and Modern Regression Models: Using Gaussian Processes to Analyze Light Curves and Improve Predictions
    Gaussian process (GP) regression is a nonparametric Bayesian approach that has been used successfully in various astronomical domains, especially in time-domain astronomy. The most common applications are the smoothing of data for interpolation and the detection of periodicities. The ability to create unbiased data-driven models without a predefined physical model can be a major advantage over conventional regression methods. Prior knowledge can be included by setting boundary conditions or constraining hyperparameter values, while unknown hyperparameters are optimized during the conditioning of the model. We have adapted and transformed previous approaches of GP regression and introduce three new applications for this regression method, especially in the context of stellar occultations: the modeling of occultation light curves, the correction of public JPL ephemerides of minor planets based on publicly available image data of the Zwicky Transient Facility, and the detection of natural satellites. We used data from observations of stellar occultations to validate the models and achieved promising results in all cases, and thus we confirmed the flexibility of GP regression models. Considering various existing use cases in addition to our novel applications, GP regression can be used to model diverse data sets addressing a wide range of problems. The accuracy of the model depends on the input data and on the set boundary conditions. Generally, high-quality data allow the usage of loose boundary conditions, while low-quality data require more restrictive boundary conditions to avoid overfitting.
  9. Kawata, D., Kawahara, H., Gouda, N., et al., (including Levine, S.), 2024, PASJ, JASMINE: Near-infrared astrometry and time-series photometry science
    The Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE) is a planned M-class science space mission by the Institute of Space and Astronautical Science, the Japan Aerospace Exploration Agency. JASMINE has two main science goals. One is Galactic archaeology with a Galactic Center survey, which aims to reveal the Milky Way's central core structure and formation history from Gaia-level (~25 ${\mu} $as) astrometry in the near-infrared (NIR) Hw band (1.0-1.6 ${\mu} $m). The other is an exoplanet survey, which aims to discover transiting Earth-like exoplanets in the habitable zone from NIR time-series photometry of M dwarfs when the Galactic Center is not accessible. We introduce the mission, review many science objectives, and present the instrument concept. JASMINE will be the first dedicated NIR astrometry space mission and provide precise astrometric information on the stars in the Galactic Center, taking advantage of the significantly lower extinction in the NIR. The precise astrometry is obtained by taking many short-exposure images. Hence, the JASMINE Galactic Center survey data will be valuable for studies of exoplanet transits, asteroseismology, variable stars, and microlensing studies, including discovery of (intermediate-mass) black holes. We highlight a swath of such potential science, and also describe synergies with other missions.
  10. Zhao, L., Dumusque, X., Ford, E., et al., (including Llama, J.), 2024, ESS, 56, 200.02, The Extreme Stellar Signals Project
    The Extreme Stellar Signals Project (ESSP) is an international research network of scientists developing methods for mitigating stellar signals. With our first round of work, we established the current state of the field through a self-consistent comparison of 21 different methods implemented on the same extreme-precision spectroscopic data from the EXPRES instrument. This talk will introduce the second round of comparisons, which makes use of contemporaneous Sun-as-a-star observations taken by HARPS, HARPS-N, EXPRES, and NEID. I will share lessons learned from comparing contemporaneous data across instruments and discuss strategies for combining data from different instruments. I will conclude with the potential and limitations of this combined data set for testing mitigation methods.
  11. Shkolnik, E., Park, N., Llama, J., 2024, ESS, 56, 203.02, Understanding Space Weather in Exoplanetary Systems: Learning from the Sun through Solar Flare and Coronal Mass Ejection Studies
    Eruptive events such as stellar flares and coronal mass ejections (CMEs; energetic and highly magnetized plasma) affect the evolution, chemistry, and habitability of planets, especially of tightly-orbiting planets. Consequently, the particle environment of the Sun, a.k.a. space weather, is continuously monitored. However, data on other stars remains limited, with no conclusively detected stellar CMEs. Our work aims to bridge this gap by correlating solar X-ray and UV flare fluxes with the mass of corresponding CMEs, observed over more than two solar cycles (23 years). We uncover a log-linear correlation between flare peak flux and CME mass, which could extend to Sun-like stars, aiding in predicting CME plasma mass. These predictions are vital for models assessing the impact of energetic particles on planetary atmospheres, thus contributing to a better understanding of planet habitability in different stellar environments.
  12. Llama, J., Brewer, J., Zhao, L., et al., 2024, ESS, 56, 601.04, Disentangling planetary and stellar signals by observing the Sun with the EXtreme PREcision Spectrograph (EXPRES)
    The signal induced by a temperate, terrestrial planet orbiting a Sun-like star is an order of magnitude smaller than the host stars' intrinsic variability. Understanding stellar activity is, therefore, a fundamental obstacle in confirming the smallest exoplanets. The EXtreme PREcision Spectrograph (EXPRES) has been obtaining EPRV measurements of stars to search for Earth-sized exoplanets since 2019. Recently, we integrated a solar feed into EXPRES to observe the Sun during the day in an analogous way to the stars at night. The Lowell Observatory Solar Telescope (LOST) is a 70-mm aperture lens that is fiber-fed into EXPRES. In clear conditions, the EXPRES solar observations have a cadence of approximately 300-s and single measurement uncertainty of just 35 cm/s. Since first light in late 2020, we have obtained over 35,000 RV measurements of the Sun. In this presentation, I will present our first results including comparisons with other solar telescopes, comparisons with disk-resolved data from NASA's Solar Dynamics Observatory, and prospects for correcting the RV variability induced by stellar activity.
  13. Clark, C., van Belle, G., Horch, E., et al., (including von Braun, K., Skiff, B., Llama, J.), 2024, ESS, 56, 614.01, Planet-Hosting M Dwarfs Have Fewer Close-In Stellar Companions
    Stellar companions are known to affect multiple facets of exoplanet formation, evolution, detection, and characterization. In particular, recent studies of FGK stars from Kepler, K2, and TESS have shown that stellar companions to planet-hosting stars have a projected separation distribution that peaks at a larger value than what is expected from non-planet-hosting field stars. This is likely the result of close-in companions affecting and perhaps inhibiting the planet formation process. To test if this is true for the lowest-mass stars as well, we have conducted a volume-limited, high-resolution imaging survey of M dwarfs out to 15 pc. The 15-pc POKEMON sample consists of 455 M dwarfs from M0V through M9V, making it one of the most complete surveys across the broad range of M-dwarf masses. We find a stellar multiplicity rate of 24.02.0%, and a projected separation distribution that peaks at 6.81 au, which is consistent with previous studies of M-dwarf multiplicity. However, the projected separation distribution of the planet-hosting stars in the sample is shifted significantly out to 198 au similar to what has been found for the FGK stars. These results indicate that the presence of a stellar companion impacts the formation and evolution of any planets around our low-mass neighbors.
  14. Kutra, T., 2024, ESS, 56, 622.04, A New Steady State of Irradiated Disks: the Staircase
    Much of a protoplanetary disk is thermally controlled by the central irradiation. Such a disk, thought to have a flaring shape, is likely unstable to the so-called 'irradiation instability'. But what's the outcome of such an instability? In particular, is it possible that such a disk settle into a shape that is immune to the instability? We combine Athena++ with a simplified thermal treatment to show that passively heated disks settle into a staircase-like steady state. The steady state is punctuated by bright rings and dark gaps, with the bright rings intercepting the lion's share of stellar illumination, and the dark gaps lying in shadows. The optical surface of such a disk (height at which starlight is absorbed) resembles a staircase. We use the RADMC3d code to show that the steady state we find is also in good thermal equilibrium. The novel staircase state, if confirmed by more sophisticated radiative hydrodynamic simulations, has a range of implications for disk evolution and planet formation.
  15. Richey-Yowell, T., Shkolnik, E., Llama, J., et al., 2024, ESS, 56, 624.42, In Search of Exoplanet Infrared Aurorae: Constraints from Two Hot Jupiters
    Infrared (IR) aurorae on exoplanets are dynamic probes of star-planet interactions, with strong aurorae providing detections of the planetary magnetic fields, constraining host-star wind properties, and delivering information on the thermal structures of planets. Decades of work towards understanding the IR aurorae of Jupiter, Saturn, and Uranus prepared us for applying similar methods to exoplanets. We present the history of IR auroral searches and our team's own recent work with Keck NIRSPEC to search for molecular H3+ auroral signatures on the hot Jupiters WASP-69b and WASP-80b. We further discuss the need for improved modeling work and advancements in technology to find these elusive auroral signatures on exoplanets.
  16. Thieberger, C., Robinson, T., Hanley, J., 2024, ESS, 56, 627.05, Characterization of Hazy Planetary Atmospheres
    The Habitable Worlds Observatory (HWO) is an under-development NASA space telescope mission concept that will observe exoplanets by direct imaging to study their atmospheres. Exoplanets that have been observed thus far, mainly with transit spectroscopy, have shown a ubiquitous presence of hazes in clouds in their atmospheres. Characterization of these atmospheres relies on modeling for interpretation of the observed spectra. However, current atmospheric models for exoplanets generally adopt untested, low-complexity treatments for hazes and clouds, thus limiting the analysis of the data. In order to prepare an accurate model ahead of the HWO data collection, we must turn to analog environments in order to test and fit our haze parameterizations. Objects within our Solar System make for excellent candidates to develop this model since they are ground-truthed, thus enabling identification of biases that occur when aerosols are treated in a simplified manner. Within our Solar System, Titan is likely the best analog to hazy exoplanets. The Cassini-Huygens mission and numerous ground-based telescope campaigns provide essential ground truth observations of Titan, allowing us to check model retrievals against measured values to ensure accuracy. We developed a haze parameterization model with wavelength-dependent expressions for absorption and scattering efficiencies, as well as single-scattering albedo. We apply our atmospheric retrieval model to visible-wavelength observations of Titan's geometric albedo from Karkoschka (1998). Preliminary results demonstrate a significant improvement from past models that do not incorporate the wavelength-dependence of atmospheric haze. We are also in the process of fitting the model to our own spectra from the Lowell Discovery Telescope's EXtreme PREcision Spectrometer (EXPRES) and Near-Infrared High-Throughput Spectrometer (NIHTS) to monitor Titan's haze and methane abundances (see Hanley et al, this conference, for more information on the observations).
  17. van Belle, G., Ciardi, D., Hillsberry, D., et al., 2024, ESS, 56, 628.18, MoonLITE: the Extreme Instrument for Extreme Solar Systems
    The MoonLITE (Lunar InTerferometry Explorer) project is a 2023 NASA Astrophysics Pioneers proposal to develop, build, fly, and operate the first separated-aperture optical interferometer in space. MoonLITE is proposed fly as a payload hosted aboard one of NASA's Commercial Lunar Payload Services (CLPS) landers, to deliver an optical interferometer to the lunar surface. Recent lunar surface operations by other telescope facilities have significantly retired the perceived risk of lunar dust contamination, and the stability of the moon's surface markedly simplifies interferometer pointing and stationkeeping requirements relative to orbital concepts. The combination of high spatial resolution from optical interferometry, with deep sensitivity from the stability of the lunar surface, would open up unprecedented discovery space for exoplanet science. After landing on the lunar surface, the CLPS rover will deploy the pre-loaded MoonLITE outboard optical element 100 meters from the lander, establishing a interferometric observatory with a single deployment. MoonLITE combines a 110 microarcsecond limiting spatial resolution with enough sensitivity to observe targets fainter than 17th magnitude in the visible. The capabilities of MoonLITE open a unique discovery space that includes direct size measurements of the smallest, coolest stellar and substellar exoplanet hosts. MoonLITE will also conduct searches for close-in stellar companions orbiting exoplanet-hosting stars that could confound future HWO observations of Earth-like planets, as well as extragalactic science at extreme levels of angular resolution. MoonLITE will open up the lunar landscape for potential SMEX and MIDEX class facilities that will measure the masses of exoplanets via astrometric surveys. Twenty percent of the observing time of this revolutionary observatory will be also made available to the broader community via a guest observer program.
  18. Hanley, J., Thieberger, C., Corlies, P., et al., (including Llama, J.), 2024, ESS, 56, 632.03, Identifying Clouds and the Vertical Abundances of Haze and Methane on Titan with Applications to Exoplanets
    Saturn's largest moon, Titan, is an excellent candidate for observational analogs of exoplanets. Titan hosts a thick atmosphere with complex organic chemistry resulting from the UV photolysis of methane and nitrogen, resulting in the formation of complex aerosols that obscure Titan's surface. Haze and clouds are expected to occur on exoplanets, potentially limiting the ability to probe the full atmosphere. Our observations demonstrate a technique for not only identifying haze and methane clouds, but also their vertical distributions (see Thieberger et al, this conference). We will present observations centered across various longitudes in order to get an integrated picture of these vertical distributions and to look for global scale and temporal differences. We use the Lowell Discovery Telescope (LDT) EXtreme PREcision Spectrometer (EXPRES) to study Titan's spectrum from ~0.4 - 0.75-m at resolution R~135,000. This slope is set by absorption and scattering of UV and visible light by aerosols, and will lead to constraints on the composition and vertical abundance of hazes in Titan's atmosphere. The high resolution also allows identification of narrow features attributed to specific molecules yet to be determined. Observations with EXPRES are sensitive to Titan's middle and upper atmosphere; we also observe with LDT's Near-Infrared High-Throughput Spectrograph (NIHTS) which is low-resolution (R~200), covering 0.86-2.4 m. Using both instruments allows access to the methane windows that can see down to Titan's surface, permitting us to complete the vertical abundance retrievals through Titan's entire atmosphere. Also, by comparing the brightness at specific wavelengths, we can monitor for any changes that might indicate cloud formation. Data from EXPRES show many features attributed to reflected sunlight, but one challenge that arises from the high spectral resolution is the issue of dividing by a reference star. Typical Solar System observations use a G2 star as a solar analog. Due to variations in composition and rotation rates between these stars and the Sun, they are not compatible with our observations. Thus we have started using the Lowell Observatory Solar Telescope (LOST) which collects EXPRES spectra of the Sun daily to divide by (see Llama et al, this conference). Our results demonstrate that probing various depths of the atmosphere is possible for exoplanets.
  19. Jackman, J., Shkolnik, E., Loyd, R., et al., (including Richey-Yowell, T., Llama, J.), 2024, MNRAS, 529, 4354, A dragon's flame of many colours: multiwavelength observations of flares from the active M binary CR Draconis
    We present the results of a multiwavelength Professional-Amateur campaign to study the behaviour of flares from the active M1.5V star binary CR Draconis. CR Dra was observed with Transiting Exoplanet Survey Satellite (TESS) 20-s photometry, Swift near-ultraviolet (NUV) grism spectroscopy and with ground-based optical photometry and spectroscopy from a global collaboration of amateur astronomers. We detected 14 flares with TESS and Swift simultaneously, one of which also had simultaneous ground-based photometry and spectroscopy. We used the simultaneous two-colour optical and NUV observations to characterize the temperature evolution of the flare and test the accuracy of using optical data to predict NUV emission. We measured a peak temperature of $7100^{+150}_{-130}$ K for this flare, cooler than the typically assumed 9000 K blackbody model used by flare studies. We also found that the 9000 K blackbody overestimated the NUV flux for other flares in our sample, which we attributed to our Swift observations occurring during flare decays, highlighting the phase-dependence for the accuracy of flare models.
  20. Thirouin, A., Sheppard, S., 2024, PSJ, 5, 84, Rotational Study of 5:3 and 7:4 Resonant Objects within the Main Classical Trans-Neptunian Belt
    The 5:3 and 7:4 mean motion resonances of Neptune are at 42.3 and 43.7 au, respectively, and overlap with objects in the classical trans-Neptunian belt (Kuiper Belt). We report the complete/partial lightcurves of 13 and 14 trans-Neptunian objects (TNOs) in the 5:3 and 7:4 resonances, respectively. We report a most likely contact binary in the 7:4 resonance, 2013 FR28, with a periodicity of 13.97 0.04 hr and a lightcurve amplitude of 0.94 0.02 mag. With a V-/U-shaped lightcurve, 2013 FR28 has one of the largest well-sampled TNO amplitudes observed with ground-based observations, comparable to the well-determined contact binary 2001 QG298. 2013 FR28 has a mass ratio q 1 with a density 1 g cm3. We find several objects with large amplitudes and classify 2004 SC60, 2006 CJ69, and 2013 BN82 as likely contact binaries and 2001 QF331, 2003 YW179, and 2015 FP345 as likely elongated objects. We observe the 17:9 resonant or classical object 2003 SP317 that we classify as a likely contact binary. A lower estimate of 10%50% and 20%55% for the fraction of (nearly) equal-sized contact binaries is calculated in the 5:3 and 7:4 resonances, respectively. Surface colors of 2004 SC60, 2013 BN82, 2014 OL394, and 2015 FP345 have been obtained. Including these colors with ones from the literature reveals that elongated objects and contact binaries share the same ultrared surface color, except ManweThorondor and 2004 SC60. Not only are the colors of the 7:4 and 5:3 TNOs similar to the cold classicals, but we demonstrate that the rotational properties of the 5:3 and 7:4 resonants are similar to those of the cold classicals, inferring a clear link between these subpopulations.
  21. Wong, I., Brown, M., Emery, J., et al., (including Grundy, W.), 2024, PSJ, 5, 87, JWST Near-infrared Spectroscopy of the Lucy Jupiter Trojan Flyby Targets: Evidence for OH Absorption, Aliphatic Organics, and CO2
    We present observations obtained with the Near Infrared Spectrograph on JWST of the five Jupiter Trojans that will be visited by the Lucy spacecraftthe PatroclusMenoetius binary, Eurybates, Orus, Leucus, and Polymele. The measured 1.75.3 m reflectance spectra, which provide increased wavelength coverage, spatial resolution, and signal-to-noise ratio over previous ground-based spectroscopy, reveal several distinct absorption features. We detect a broad OH band centered at 3 m that is most prominent on the less-red objects Eurybates, PatroclusMenoetius, and Polymele. An additional absorption feature at 3.33.6 m, indicative of aliphatic organics, is systematically deeper on the red objects Orus and Leucus. The collisional fragment Eurybates is unique in displaying an absorption band at 4.25 m that we attribute to bound or trapped CO2. Comparisons with other solar system small bodies reveal broad similarities in the 2.73.6 m bands with analogous features on Centaurs, Kuiper Belt objects (KBOs), and the active asteroid 238P. In the context of recent solar system evolution models, which posit that the Trojans initially formed in the outer solar system, the significant attenuation of the 2.73.6 m absorption features on Trojans relative to KBOs may be the result of secondary thermal processing of the Trojans' surfaces at the higher temperatures of the Jupiter region. The CO2 band manifested on the surface of Eurybates suggests that CO2 may be a major constituent in the bulk composition of Trojans, but resides in the subsurface or deeper interior and is largely obscured by refractory material that formed from the thermophysical processes that were activated during their inward migration.
  22. Clark, C., van Belle, G., Horch, E., et al., (including von Braun, K., Skiff, B., Llama, J.), 2024, AJ, 167, 174, The POKEMON Speckle Survey of Nearby M Dwarfs. III. The Stellar Multiplicity Rate of M Dwarfs within 15 pc
    M dwarfs are ubiquitous in our Galaxy, and the rate at which they host stellar companions, and the properties of these companions, provide a window into the formation and evolution of the star(s), and of any planets that they may host. The Pervasive Overview of "Kompanions" of Every M dwarf in Our Neighborhood (POKEMON) speckle survey of nearby M dwarfs is volume limited from M0V through M9V out to 15 pc, with additional targets at larger distances. In total, 1125 stars were observed, and 455 of these are within the volume-limited, 15 pc sample of M-dwarf primaries. When we combine the speckle observations with known companions from the literature, we find that the stellar multiplicity rate of M dwarfs within 15 pc is 23.5% 2.0%, and that the companion rate is 28.8% 2.1%. We also find that the projected separation distribution for multiples that are known to host planets peaks at 198 au, while the distribution for multiples that are not yet known to host planets peaks at 5.57 au. This result suggests that the presence of close-in stellar companions inhibits the formation of M-dwarf planetary systems, similar to what has been found for FGK stars.
  23. Loyd, R., Schneider, P., Jackman, J., et al., (including Llama, J.), 2024, AJ, 167, 185, Erratum: "Flares, Rotation, Activity Cycles, and a Magnetic StarPlanet Interaction Hypothesis for the Far-ultraviolet Emission of GJ 436" (2023, AJ, 165, 146)
    No abstract found.
  24. Qu, H., Sako, M., Vincenzi, M., et al., (including Kuehn, K.), 2024, ApJ, 964, 134, The Dark Energy Survey Supernova Program: Cosmological Biases from Host Galaxy Mismatch of Type Ia Supernovae
    Redshift measurements, primarily obtained from host galaxies, are essential for inferring cosmological parameters from type Ia supernovae (SNe Ia). Matching SNe to host galaxies using images is nontrivial, resulting in a subset of SNe with mismatched hosts and thus incorrect redshifts. We evaluate the host galaxy mismatch rate and resulting biases on cosmological parameters from simulations modeled after the Dark Energy Survey 5 Yr (DES-SN5YR) photometric sample. For both DES-SN5YR data and simulations, we employ the directional light radius method for host galaxy matching. In our SN Ia simulations, we find that 1.7% of SNe are matched to the wrong host galaxy, with redshift differences between the true and matched hosts of up to 0.6. Using our analysis pipeline, we determine the shift in the dark energy equation of state parameter (w) due to including SNe with incorrect host galaxy matches. For SN Iaonly simulations, we find w = 0.0013 0.0026 with constraints from the cosmic microwave background. Including core-collapse SNe and peculiar SNe Ia in the simulation, we find that w ranges from 0.0009 to 0.0032, depending on the photometric classifier used. This bias is an order of magnitude smaller than the expected total uncertainty on w from the DES-SN5YR sample of 0.03. We conclude that the bias on w from host galaxy mismatch is much smaller than the uncertainties expected from the DES-SN5YR sample, but we encourage further studies to reduce this bias through better host-matching algorithms or selection cuts.
  25. Navarro-Meza, S., Trilling, D., Mommert, M., et al., 2024, AJ, 167, 163, Taxonomy of Subkilometer Near-Earth Objects from Multiwavelength Photometry with RATIR
    We present results from observations of 238 near-Earth objects (NEOs) obtained with the RATIR instrument on the 1.5 m robotic telescope at San Pedro Martir's National Observatory in Mexico, in the frame of our multiobservatory, multifilter campaign. Our project is focused on rapid response photometric observations of NEOs with absolute magnitudes in the range 18.127.1 (diameter 600 and 10 m, respectively). Data with coverage in the near-infrared and visible range were analyzed with a nonparametric classification algorithm, while visible-only data were independently analyzed via Monte Carlo simulations and a 1-Nearest Neighbor method. The rapid response and the use of spectrophotometry allows us to obtain taxonomic classifications of subkilometer objects with small telescopes, representing a convenient characterization strategy. We present taxonomic classifications of the 87 objects observed in the visible and near-infrared. We also present the taxonomic distribution of an additional 151 objects observed in the visible. Our most accurate method suggests a nonfeatured-to-featured ratio of 0.75, which is consistent with the value found by the Mission Accessible Near-Earth Object Survey, which conducted a similar study using a spectral analysis. The results from the Monte Carlo method suggest a ratio of 0.8, although this method has some limitations. The 1-Nearest Neighbor method showed to be not suitable for NEO classifications.
  26. Proudfoot, B., Ragozzine, D., Thatcher, M., et al., (including Grundy, W.), 2024, AJ, 167, 144, Beyond Point Masses. II. Non-Keplerian Shape Effects Are Detectable in Several TNO Binaries
    About 40 trans-Neptunian binaries (TNBs) have fully determined orbits with about 10 others being solved except for breaking the mirror ambiguity. Despite decades of study, almost all TNBs have only ever been analyzed with a model that assumes perfect Keplerian motion (e.g., two point masses). In reality, all TNB systems are non-Keplerian due to nonspherical shapes, possible presence of undetected system components, and/or solar perturbations. In this work, we focus on identifying candidates for detectable non-Keplerian motion based on sample of 45 well-characterized binaries. We use MultiMoon, a non-Keplerian Bayesian inference tool, to analyze published relative astrometry allowing for nonspherical shapes of each TNB system's primary. We first reproduce the results of previous Keplerian fitting efforts with MultiMoon, which serves as a comparison for the non-Keplerian fits and confirms that these fits are not biased by the assumption of a Keplerian orbit. We unambiguously detect non-Keplerian motion in eight TNB systems across a range of primary radii, mutual orbit separations, and system masses. As a proof of concept for non-Keplerian fitting, we perform detailed fits for (66652) Borasisi-Pabu, possibly revealing a J 2 0.44, implying Borasisi (and/or Pabu) may be a contact binary or an unresolved compact binary. However, full confirmation of this result will require new observations. This work begins the next generation of TNB analyses that go beyond the point mass assumption to provide unique and valuable information on the physical properties of TNBs with implications for their formation and evolution.
  27. Chandler, C., Trujillo, C., Oldroyd, W., et al., (including Kueny, J.), 2024, AJ, 167, 156, The Active Asteroids Citizen Science Program: Overview and First Results
    We present the Citizen Science program Active Asteroids and describe discoveries stemming from our ongoing project. Our NASA Partner program is hosted on the Zooniverse online platform and launched on 2021 August 31, with the goal of engaging the community in the search for active asteroidsasteroids with comet-like tails or comae. We also set out to identify other unusual active solar system objects, such as active Centaurs, active quasi-Hilda asteroids (QHAs), and Jupiter-family comets (JFCs). Active objects are rare in large part because they are difficult to identify, so we ask volunteers to assist us in searching for active bodies in our collection of millions of images of known minor planets. We produced these cutout images with our project pipeline that makes use of publicly available Dark Energy Camera data. Since the project launch, roughly 8300 volunteers have scrutinized some 430,000 images to great effect, which we describe in this work. In total, we have identified previously unknown activity on 15 asteroids, plus one Centaur, that were thought to be asteroidal (i.e., inactive). Of the asteroids, we classify four as active QHAs, seven as JFCs, and four as active asteroids, consisting of one main-belt comet (MBC) and three MBC candidates. We also include our findings concerning known active objects that our program facilitated, an unanticipated avenue of scientific discovery. These include discovering activity occurring during an orbital epoch for which objects were not known to be active, and the reclassification of objects based on our dynamical analyses.
  28. Glein, C., Grundy, W., Lunine, J., et al., 2024, Icar, 412, 115999, Moderate D/H ratios in methane ice on Eris and Makemake as evidence of hydrothermal or metamorphic processes in their interiors: Geochemical analysis
    Dwarf planets Eris and Makemake have surfaces bearing methane ice of unknown origin. This ice can provide important insights into the origin and evolution of volatiles in the outer solar system. Deuterium/hydrogen (D/H) ratios were recently determined from James Webb Space Telescope (JWST) observations of Eris and Makemake (Grundy et al., 2024b), giving us new clues to decipher the origin of methane. Here, we develop geochemical models to test if the origin of methane could be primordial, derived from CO2 or CO ("abiotic"), or sourced by organics ("thermogenic"). We find that primordial methane (as currently understood) is inconsistent with the observational data, whereas both abiotic and thermogenic methane can have D/H ratios that overlap the observed ranges. This suggests that Eris and Makemake either never acquired much methane during their formation, or their original inventories were removed and then replaced by internally produced methane. Because producing abiotic or thermogenic methane likely requires temperatures above 150 C, we infer that Eris and Makemake have rocky cores that underwent substantial radiogenic heating. Their cores may still be warm/hot enough to make methane. This heating could have driven hydrothermal circulation at the bottom of an ice-covered ocean to generate abiotic methane, and/or metamorphic reactions involving accreted organic matter could have occurred in response to heating in the deeper interior, generating thermogenic methane. Additional analyses of relevant thermal evolution model results and theoretical predictions of the D/H ratio of methane in the solar nebula support our findings of elevated subsurface temperatures and an apparent lack of primordial methane on Eris and Makemake. It remains an open question whether their D/H ratios may have evolved subsequent to methane outgassing. We also suggest that lower-than-expected D/H and 84Kr/CH4 ratios in Titan's atmosphere disfavor a primordial origin of methane there as well. Recommendations are given for future activities to further test proposed scenarios of abiotic and thermogenic methane production on Eris and Makemake, and to explore these worlds up close so that we can see if they bear additional evidence of endogenic processes.
  29. Kao, M., Pineda, J., 2024, MNRAS, Binarity enhances the occurrence rate of radiation belt emissions in ultracool dwarfs
    Despite a burgeoning set of ultracool dwarf (M7) radio detections, their radio emissions remain enigmatic. Open questions include the plasma source and acceleration mechanisms for the non-auroral 'quiescent' component of these objects' radio emissions, which can trace Jovian synchrotron radiation belt analogs. Ultracool dwarf binary systems can provide test beds for examining the underlying physics for these plasma processes. We extend a recently developed occurrence rate calculation framework to compare the quiescent radio occurrence rate of binary systems to single objects. This generalized and semi-analytical framework can be applied to any set of astrophysical objects conceptualized as unresolved binary systems with approximately steady-state emission or absorption. We combine data available in the literature to create samples of 179 single ultracool dwarfs (82 M dwarfs, 74 L dwarfs, and 23 T/Y dwarfs) and 27 binary ultracool dwarf systems. Using these samples, we show that quiescent radio emissions occur in $54^{+11}_{-11}$ - $65^{+11}_{-12}$ per cent of binaries where both components are ultracool dwarfs, depending on priors. We also show that binarity enhances the ultracool dwarf quiescent radio occurrence rate relative to their single counterparts. Finally, we discuss potential implications for the underlying drivers of ultracool dwarf quiescent radio emissions, including possible plasma sources.
  30. Gatti, M., Jeffrey, N., Whiteway, L., et al., (including Kuehn, K.), 2024, PhRvD, 109, 063534, Dark Energy Survey Year 3 results: Simulation-based cosmological inference with wavelet harmonics, scattering transforms, and moments of weak lensing mass maps. Validation on simulations
    Beyond-two-point statistics contain additional information on cosmological as well as astrophysical and observational (systematics) parameters. In this methodology paper we provide an end-to-end simulation-based analysis of a set of Gaussian and non-Gaussian weak lensing statistics using detailed mock catalogs of the Dark Energy Survey (DES). We implement: 1) second and third moments; 2) wavelet phase harmonics (WPH); 3) the scattering transform (ST). Our analysis is fully based on simulations, it spans a space of seven w CDM cosmological parameters, and it forward models the most relevant sources of systematics of the data (masks, noise variations, clustering of the sources, intrinsic alignments, and shear and redshift calibration). We implement a neural network compression of the summary statistics, and we estimate the parameter posteriors using a likelihood-free-inference approach. We validate the pipeline extensively, and we find that WPH exhibits the strongest performance when combined with second moments, followed by ST, and then by third moments. The combination of all the different statistics further enhances constraints with respect to second moments, up to 25 percent, 15 percent, and 90 percent for S8 , m, and the figure-of-merit FoMS8,m , respectively. We further find that non-Gaussian statistics improve constraints on w and on the amplitude of intrinsic alignment with respect to second moments constraints. The methodological advances presented here are suitable for application to Stage IV surveys from Euclid, Rubin-LSST, and Roman with additional validation on mock catalogs for each survey. In a companion paper we present an application to DES Year 3 data.
  31. Naidu, S., Chesley, S., Moskovitz, N., et al., 2024, PSJ, 5, 74, Orbital and Physical Characterization of Asteroid Dimorphos Following the DART Impact
    The Double Asteroid Redirection Test (DART) mission impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos, on 2022 September 26 UTC. We estimate the changes in the orbital and physical properties of the system due to the impact using ground-based photometric and radar observations, as well as DART camera observations. Under the assumption that Didymos is an oblate spheroid, we estimate that its equatorial and polar radii are 394 11 m and 290 16 m, respectively. We estimate that the DART impact instantaneously changed the along-track velocity of Dimorphos by 2.63 0.06 mm s1. Initially, after the impact, Dimorphos's orbital period had changed by 32.7 minutes 16 s to 11.377 0.004 hr. We find that over the subsequent several weeks the orbital period changed by an additional 34 15 s, eventually stabilizing at 11.3674 0.0004 hr. The total change in the orbital period was 33.25 minutes 1.5 s. The postimpact orbit exhibits an apsidal precession rate of 6.7 0.2 day1. Under our model, this rate is driven by the oblateness parameter of Didymos, J 2, as well as the spherical harmonics coefficients, C 20 and C 22, of Dimorphos's gravity. Under the assumption that Dimorphos is a triaxial ellipsoid with a uniform density, its C 20 and C 22 estimates imply axial ratios, a/b and a/c, of about 1.3 and 1.6, respectively. Preimpact images from DART indicate Dimorphos's shape was close to that of an oblate spheroid, and thus our results indicate that the DART impact significantly altered the shape of Dimorphos.
  32. Proudfoot, B., Ragozzine, D., Giforos, W., et al., (including Grundy, W.), 2024, PSJ, 5, 69, Beyond Point Masses. III. Detecting Haumea's Nonspherical Gravitational Field
    The dwarf planet Haumea is one of the most compelling trans-Neptunian objects to study, hosting two small, dynamically interacting satellites, a family of nearby spectrally unique objects, and a ring system. Haumea itself is extremely oblate due to its 3.9 hr rotation period. Understanding the orbits of Haumea's satellites, named Hi'iaka and Namaka, requires detailed modeling of both satellitesatellite gravitational interactions and satellite interactions with Haumea's nonspherical gravitational field (parameterized here as J 2). Understanding both of these effects allows for a detailed probe of the satellites' masses and Haumea's J 2 and spin pole. Measuring Haumea's J 2 provides information about Haumea's interior, possibly determining the extent of past differentation. In an effort to understand the Haumea system, we have performed detailed non-Keplerian orbit fitting of Haumea's satellites using a decade of new, ultra-precise observations. Our fits detect Haumea's J 2 and spin pole at 2.5 confidence. Degeneracies present in the dynamics prevent us from precisely measuring Haumea's J 2 with the current data, but future observations should enable a precise measurement. Our dynamically determined spin pole shows excellent agreement with past results, illustrating the strength of non-Keplerian orbit fitting. We also explore the spinorbit dynamics of Haumea and its satellites, showing that axial precession of Hi'iaka may be detectable over decadal timescales. Finally, we present an ephemeris of the Haumea system over the coming decade, enabling high-quality observations of Haumea and its satellites for years to come.
  33. Cross, D., Thoron, G., Jeltema, T., et al., (including Kuehn, K.), 2024, MNRAS, 529, 52, Examining the self-interaction of dark matter through central cluster galaxy offsets
    While collisionless cold dark matter models have been largely successful in explaining a wide range of observational data, some tensions still exist, and it remains possible that dark matter possesses a non-negligible level of self-interactions. In this paper, we investigate a possible observable consequence of self-interacting dark matter: offsets between the central galaxy and the centre of mass of its parent halo. We examine 23 relaxed galaxy clusters in a redshift range of 0.1-0.3 drawn from clusters in the Dark Energy Survey and the Sloan Digital Sky Survey which have archival Chandra X-ray data of sufficient depth for centre and relaxation determination. We find that most clusters in our sample show non-zero offsets between the X-ray centre, taken to be the centroid within the cluster core, and the central galaxy position. All of the measured offsets are larger, typically by an order of magnitude, than the uncertainty in the X-ray position due to Poisson noise. In all but six clusters, the measured offsets are also larger than the estimated, combined astrometric uncertainties in the X-ray and optical positions. A more conservative cut on concentration to select relaxed clusters marginally reduces but does not eliminate the observed offset. With our more conservative sample, we find an estimated median X-ray to central galaxy offset of $\mu = 6.0 ^{+ 1.4}_{- 1.5}$ kpc. Comparing to recent simulations, this distribution of offsets is consistent with some level of dark matter self-interaction, though further simulation work is needed to place constraints.
  34. Grundy, W., Tegler, S., Steckloff, J., et al., (including Koga, K., Hanley, J.), 2024, Icar, 410, 115767, Laboratory measurement of volatile ice vapor pressures with a quartz crystal microbalance
    Nitrogen, carbon monoxide, and methane are key materials in the far outer Solar System where their high volatility enables them to sublimate, potentially driving activity at very low temperatures. Knowledge of their vapor pressures and latent heats of sublimation at relevant temperatures is needed to model the processes involved. We describe a method for using a quartz crystal microbalance to measure the sublimation flux of these volatile ices in the free molecular flow regime, accounting for the simultaneous sublimation from and condensation onto the quartz crystal to derive vapor pressures and latent heats of sublimation. We find vapor pressures to be somewhat lower than previous estimates in literature, with carbon monoxide being the most discrepant of the three species, almost an order of magnitude lower than had been thought. These results have important implications across a variety of astrophysical and planetary environments.
  35. Grundy, W., Wong, I., Glein, C., et al., 2024, Icar, 411, 115923, Measurement of D/H and 13C/12C ratios in methane ice on Eris and Makemake: Evidence for internal activity
    James Webb Space Telescope's NIRSpec infrared imaging spectrometer observed the outer solar system dwarf planets Eris and Makemake in reflected sunlight at wavelengths spanning 1 through 5 m. Both objects have high albedo surfaces that are rich in methane ice, with a texture that permits long optical path lengths through the ice for solar photons. There is evidence for N2 ice absorption around 4.2 m on Eris, though not on Makemake. No CO ice absorption is seen at 4.67 m on either body. For the first time, absorption bands of two heavy isotopologues of methane are observed at 2.615 m (13CH4), 4.33 m (12CH3D), and 4.57 m (12CH3D). These bands enable us to measure D/H ratios of (2.5 0.5) 10-4 and (2.9 0.6) 10-4, along with 13C/12C ratios of 0.012 0.002 and 0.010 0.003 in the surface methane ices of Eris and Makemake, respectively. The measured D/H ratios are much lower than that of presumably primordial methane in comet 67P/Churyumov-Gerasimenko, but they are similar to D/H ratios in water in many comets and larger outer solar system objects. This similarity suggests that the hydrogen atoms in methane on Eris and Makemake originated from water, indicative of geochemical processes in past or even ongoing hot environments in their deep interiors. The 13C/12C ratios are consistent with commonly observed solar system values, suggesting no substantial enrichment in 13C as could happen if the methane currently on their surfaces was the residue of a much larger inventory that had mostly been lost to space. Possible explanations include geologically recent outgassing from the interiors as well as processes that cycle the surface methane inventory to keep the uppermost surfaces refreshed.
  36. de Souza Feliciano, A., Alvarez-Candal, A., Brunetto, R., et al., (including Grundy, W.), 2024, jwst, 6064, Constraining the dynamical evolution of the outer solar system with trans-Neptunian binaries
    Trans-Neptunian objects (TNOs) are icy remnants of the planetary formation that orbit the Sun in the region beyond Neptune. We propose to resolve a sample of 10 trans-Neptunian binaries (TNBs) of similar and different sizes with tight and wide separations using three sets of NIRCAM filters. The combination of the physical and the compositional properties of the binary systems in our sample could constrain the formation scenario cases due to impact, or streaming instabilit in the early trans-Neptunain region. One portion of our sample is not explained by the current binary formation models since they have similar size (that could be compatible with the streaming instability) but tight separation (as the satellites of the larger TNOs, that could have been formed by impacts). The characterization of the surface composition of both components is crucial to address that matter. Due to their spatial separation, NIRSpec is not suitable for this task. Through the combination of the short and long filters of NIRCAM with the compositional map of the trans-Neptunian region done in the first cycle of JWST, this proposal has potential to constrain proposed formation models and provide an initial input for the expansion of dynamic and evolution theories for some TNBs.
  37. Rector, T., Prato, L., 2024, AAS, 243, 128.01, Caught in the Act: Dozens of New Herbig-Haro Objects Reveal Waves of Star Formation in the Aquila Rift
    The extensive Aquila Rift dark cloud complex stretches across the northern hemisphere summer Milky Way. It contains at least 100,000 solar masses of molecular gas, yet only a handful or two of young stars had been identified in the Rift, raising questions about the apparent paucity of star forming activity. Although the Herschel mission detected several hundred embedded cores, an in-between generation of young protostars has not been previously seen. We have surveyed Aquila for Herbig-Haro outflows using the Blanco 4-meter telescope with DECam, a unique facility+instrument combination that offers high sensitivity, wide (3 square degrees) field of view, and arcsecond resolution. Observations with H-alpha, [SII], g' and i' narrow and broad band filters have yielded 45 new HH object detections, allowing us to map the distribution of over 100 embedded young stars in the Rift cloud cores. We compare the distribution of molecular and atomic gas in Aquila to the location of the HH objects in order to understand the broad context for star formation in a giant cloud complex. Differences between the Galactic location of the Rift and other similar regions with more evolved young star populations may provide clues to the chronology of star formation in our Galactic region.
  38. Hyden, J., Prato, L., Knowlton, P., et al., (including Kutra, T., Skiff, B.), 2024, AAS, 243, 176.01, A Database for Young Binary Stars
    Circumstellar disks are the sites of planet formation. Most solar analogs are found in binary systems; therefore, understanding how these systems influence circumstellar disk evolution is important. The occurrence of planet formation around binaries is low but not zero, raising the question of what drives or inhibits planet formation in these systems. Our goal is to identify which stellar or system properties influence planet formation via disk dissipation. Our dataset will combine state-of-the-art observations and archival data of approximately 100 binary systems from Keck, the VLT and ALMA, providing years of high-quality spectra for analysis. With the Young Binary Star Database, we will provide a comprehensive archive of high-resolution infrared data, including uniformly derived stellar parameters and reduced spectra, to the community. The database is meticulously maintained using MySQL and JavaScript, while incorporating automated Python scripts for seamless updates, providing a significant and up-to-date resource for the scientific community. The finalized database will illuminate how the interplay between stellar and system properties in binaries impacts disk formation, evolution, and planet formation.
  39. Knowlton, P., Prato, L., Kutra, T., et al., (including Hyden, J.), 2024, AAS, 243, 176.07, Stars and Circumstellar Disks in Close Young Binary Systems
    Most stars are located in binary/multiple systems, therefore a complete picture of planet formation requires incorporating the impact of binary systems. Although fewer planets form around stars in multiple systems, astronomers have discovered hundreds of circumstellar exoplanets in binaries. Theoretical and observational evidence suggests that close binaries, with separations <50 AU, have smaller and shorter-lived disks than their single-star or wide binary counterparts. We aim to correlate well-determined stellar properties with circumstellar disk characteristics in order to understand their influence on the formation of planets. Using the Keck II and VLT telescopes, we have collected high-resolution (R=30,000), near-infrared spectra of the individual components in 100 young binary systems with separations from ~10 to several hundred AU. Our analyses focus on absorption lines highly sensitive to stellar and disk parameters such as effective temperature, veiling, surface gravity, surface-averaged magnetic field strength, and projected rotational velocity, extracted by fitting the observed spectra to synthetic models. Statistical tests will reveal how stellar properties impact circumstellar material and either permit or impede the formation of planets. Uniformly-derived disk and stellar parameters and the observed spectra will be made publicly available on the Young Binary Star Database.
  40. Prato, L., Knowlton, P., Hyden, J., et al., (including Kutra, T.), 2024, AAS, 243, 176.09, Extreme Veiling Variability and Circumstellar Disk Evolution in the UY Aur Infrared Companion
    Historically the UY Aur system has varied in optical light by many magnitudes; in the early 1990s, the 0.9 arcsecond binary component was identified as an infrared companion (IRC). The stars have similar spectral types, K7 and M1 for the A and B components, respectively. Adaptive optics imaging has not revealed any additional visual components in the system. Over the past 20 years, a dozen high-resolution (R=30,000 or higher), infrared spectra have demonstrated stable and consistent results for the primary component but extreme variability in the IRC: at times the spectrum manifests normal absorption lines and in some cases within months the absorption lines disappear completely. We interpret this behavior as extreme veiling variability and in this contribution we explore the implications for accretion and inner disk structure and evolution in the IRC. This research was supported in part by NSF awards AST-1313399 and AST-2109179.
  41. Brown, C., Richey-Yowell, T., 2024, AAS, 243, 259.14, Assessing Mg I Activity with Rotation and Age for FGK Stars
    A thorough understanding of how stellar activity, age, and rotation are connected is crucial for accurately modeling and predicting the underlying physical processes present in all types of stars. In general, we observe that a star's rotation slows down as it ages due to magnetic braking. This spin down relationship is relatively predictable for certain classes of stars (e.g. F and G stars), but K stars have an interesting stalling period where they rotate at a constant rate for up to 1.4 Gyr before resuming their spin down. To better understand age-activity-rotation relations and how this unique K star behavior contributes, we build on previous observational work focused on measuring the activity of the corona, transition region, and upper chromosphere of K stars by examining the activity of the lower chromosphere. We accomplished this by analyzing the Mg I line at 8809.2 angstroms of 49 K star targets; we then compared our results to the measured Mg I activity of young F and G stars found in a similar observational study by Yamashita et al. (2022). We found that while the Mg I emission line is a good activity marker in young F and G stars, it is an absorption feature and therefore a poor activity marker in older K star targets. We plan to observe young K star targets to see if a trend exists between lower chromospheric activity and age. If not, this may suggest that K stars have a less-active lower chromosphere than other types of stars.
  42. Nelsen, M., Ragozzine, D., Proudfoot, B., et al., (including Grundy, W.), 2024, AAS, 243, 340.04, Altjira: A Potential Hierarchical Triple Trans-Neptunian Object Discovered through non-Keplerian Motion
    At the edge of the solar system is a region of icy small bodies called the Kuiper Belt. Some of these objects are binaries and when we observe and track their motion, we can then measure many qualities of the objects dynamically, such as mass, orbit, density, and shape. Most of the known objects appear to have only two components, but there is a single known hierarchical triple system with three nearly-equal mass components called (47171) Lempo (Benecchi et al. 2010). A hierarchical triple is so called because when there are three nearly-equal size objects, the only stable configuration is two objects orbiting closely with a third object orbiting further away. Lempo was originally thought to be a binary, but a detailed analysis of the very highest-resolution Hubble Space Telescope images was barely able to resolve the inner binary. So far, no other hierarchical triples have been found in the solar system, due to their rarity and the resolution capabilities of telescopes. Discovering more hierarchical triples will help constrain the streaming instability model of planet formation (Nesvorny et al. 2022). We present evidence for a new hierarchical triple, (148780) Altjira (2001 UQ18), based on non-Keplerian dynamical modeling of the two observed components. Our non-Keplerian analysis includes data over 17 years (including data from ongoing HST Program 17206) which can detect the orbital precession caused by non-spherical shapes and/or unresolved inner binaries. Our analysis shows that Altjira has very strong and statistically significant oblateness (J2), which is best explained as an inner binary. We also find an excellent fit with a hierarchical triple model where the inner binary is unresolved. This potential discovery of the second hierarchical triple in the solar system will help provide new insights into planet formation from these primordial objects.
  43. Brewer, J., Zhao, L., Llama, J., 2024, AAS, 243, 352.01, What do Planetary Architectures Really Look Like? New Insights from EXPRES.
    Our view of planetary system architectures is heavily influenced by the biases in our detection methods. Transit survey statistics tell us that there are plenty of small planets, between the radius of Earth and Neptune, at least on orbits shorter than about 40 days. RV surveys have identified a handful of these interior planets, but their small size has limited their detection, even at these close-in orbits. The long time baselines of RV surveys have allowed us to identify many longer period planets, but they are typically larger than Neptune. This leaves large gaps in our knowledge, even in well studied systems. Extreme Precision RV instruments are starting to fill in those gaps. The EXtreme PREcision Spectrometer (EXPRES) and the high cadence 100 Earths Survey has been searching for these missing planets since August 2019. We have found new planets in systems that have been observed for 30 years. I will present our latest results including new planet detections and our plans to reach even smaller signals.
  44. Moreland, J., Clark, C., van Belle, G., et al., (including von Braun, K.), 2024, AAS, 243, 355.07, The POKEMON Speckle Survey of Nearby M dwarfs. The Stellar Multiplicity Rate of M Dwarfs by Spectral Subtype
    M type stars are strong candidate exoplanet hosts due to their abundance, longevity, small sizes, and low luminosities. Yet stellar multiples involving these M type stars, specifically M type dwarfs, can induce false positives and overall complicate the process of exoplanet detection and characterization. We have therefore carried out the Pervasive Overview of Kompanions of Every M dwarfs in Our Neighborhood (POKEMON) speckle survey. The purpose of this study is to investigate the stellar multiplicity rate of nearby M dwarfs and how stellar multiplicity relates to the changes as a function of spectral subtype spectral subtype at the low mass end of the main sequence, using photometric data from M type dwarf stars to classify them. In this study, we use the sedFit code, a code designed to read in photometric data and fit it to a list of given template photometric data sets of stars of varying spectral type and luminosity class. Using this code, in conjunction with photometric data collected by 2MASS, Gaia, and the Lowell Observatory's Titan Monitor, we have accurately classified the spectral subtypes of 852 targets from the POKEMON survey. Using this information, in conjunction with the known multicity of the stars in the POKEMON survey, we were able to accurately describe the relationship between stellar multiplicity stars and spectral type for the M dwarfs. We also plan to use these spectral types to update the mass ratio and orbital period distributions for M-dwarf multiples within 15 parsecs to gain additional understanding of M-dwarf formation and evolution, and of the relationship between the properties of stellar multiples and any planets that they host.
  45. Villa, K., Knight, M., Schleicher, D., et al., (including Skiff, B.), 2024, AAS, 243, 363.05, Morphological Comparison of CN and OH in Comet Comae
    While comet morphology has been analyzed for individual comets in the past (such as 103P/Hartley 2, 46P/Wirtanen, and 41P/Tuttle-Giacobini-Kresak), in this work we attempt to make the first large-scale comparison of CN and OH gas morphology across a range of comets. Recent data have shown unexpected differences in CN and OH morphology in some instances, with OH often appearing to originate from an extended coma source, e.g., icy grains. However, not enough comets have yet been analyzed collectively to form a general assessment of the correlation, or lack thereof, between CN and OH morphology. Our project attempts to do so by analyzing data from the past two decades at the same time and in a uniform manner. We have identified nearly 50 comets for which images were acquired with the comet narrowband CN and OH filters in our archive of data taken using various telescopes, primarily the Lowell Discovery Telescope (4.3-m) and Lowell 42in Hall Telescope. Using standard image enhancement techniques, we are analyzing the spatial distribution of CN and OH and attempting to correlate these with orbital parameters (to include perihelion distance q, orbit eccentricity e, inclination i, and Tisserand parameter TJ ) as well as inherent comet characteristics (i.e. chemical composition). We are comparing CN and OH imagery both visually and quantitatively to identify trends. Further analysis and image refinement will be completed to demonstrate correlations that may be indicative of a comet's dynamical or physical properties, as well as potentially trace gases to source regions on the nucleus or in the tail. This work tests the classical picture of comet activity as driven by the sublimation of water ice when heated bythe Sun inside the snow line; we will also investigate whether ices other than water (e.g., CO and CO2 ) are more significant to comet activity than previously thought.
  46. Archer, H., Hunter, D., Elmegreen, B., et al., 2024, AAS, 243, 404.11, Probing the Relationship Between Early Star Formation and CO in the Dwarf Irregular Galaxy WLM with JWST
    Dwarf irregular (dIrr) galaxies in the local universe offer a unique window into low-metallicity star formation. These low-metallicity environments strongly affect the formation and structure of molecular clouds, which are primarily composed of H2 but often traced using low rotational transitions of CO, compared to those in higher-metallicity galaxies. In a pioneering study, Rubio et al. (2015) mapped 10 CO cores with ALMA in the dIrr galaxy WLM, which has an oxygen abundance only 13% of solar. Archer et al. (2022) then examined the environments and star-forming regions surrounding the 10 CO cores, plus an additional 47 subsequently detected, in WLM but found no clear properties driving the formation of the cores. Now, thanks to JWST's exceptional resolution and sensitivity, we can investigate the role of resolved CO cores in WLM's young star-forming regions. In this study, we analyze images of WLM in the JWST F090W, F150W, F250M, and F430M filters from the ERS Program #1334 to examine the relationship between early star formation and the presence of CO cores. We compare properties, including temperature and mass, of the embedded star-forming regions near CO cores with those in other parts of the galaxy. We find shared characteristics in embedded clusters across diverse environments, regardless of proximity to FUV emission indicative of recent star formation or presence of CO cores. Any link between CO core location and early star formation at low metallicities therefore remains elusive. Funding for this work was provided by NSF to D.H. through grant AST-1907492.
  47. Kutra, T., 2024, AAS, 243, 413.04D, A New Steady State of Irradiated Disks: the Staircase
    Much of a protoplanetary disk is thermally controlled by the central irradiation. Such a disk, thought to have a flaring shape, is likely unstable to the so-called 'irradiation instability'. But what's the outcome of such an instability? In particular, is it possible that such a disk settle into a shape that is immune to the instability? We combine Athena++ with a simplified thermal treatment to show that passively heated disks settle into a staircase-like steady state. The steady state is punctuated by bright rings and dark gaps, with the bright rings intercepting the lion's share of stellar illumination, and the dark gaps lying in shadows. The optical surface of such a disk (height at which starlight is absorbed) resembles a staircase. We use the RADMC3d code to show that the steady state we find is also in good thermal equilibrium. The novel staircase state, if confirmed by more sophisticated radiative hydrodynamic simulations, has a range of implications for disk evolution and planet formation.
  48. Clark, C., van Belle, G., Horch, E., et al., (including von Braun, K., Skiff, B.), 2024, AAS, 243, 447.01, Planet-Hosting M Dwarfs Have Fewer Close-In Stellar Companions
    Stellar companions are known to affect multiple facets of exoplanet formation, evolution, detection, and characterization. In particular, recent studies of FGK stars from Kepler, K2, and TESS have shown that stellar companions to planet-hosting stars have a projected separation distribution that peaks at a larger value than what is expected from non-plant-hosting field stars. This is likely the result of close-in companions affecting and perhaps inhibiting the planet formation process. To test if this is true for the lowest-mass stars as well, we have conducted a volume-limited, high-resolution imaging survey of M dwarfs out to 15 pc. The 15-pc POKEMON sample consists of 454 M dwarfs from M0V through M9V, making it one of the most complete surveys across the broad range of M-dwarf masses. We find a stellar multiplicity rate of 25.12.0%, and a projected separation distribution that peaks at 14.6 au, which is consistent with previous studies of M-dwarf multiplicity. However, the projected separation distribution of the planet-hosting stars in the sample is shifted significantly - out to 305 au similar to what has been found for the FGK stars. These results indicate that the presence of a stellar companion impacts the formation and evolution of any planets around our low-mass neighbors.
  49. van Belle, G., Ciardi, D., Hillsberry, D., et al., 2024, AAS, 243, 450.08, MoonLITE: the Lunar InTerferometry Explorer
    The MoonLITE (Lunar InTerferometry Explorer) project is a 2023 NASA Astrophysics Pioneers proposal to develop, build, fly, and operate the first separated-aperture optical interferometer in space, delivering faint, sub-milliarcsecond science results. MoonLITE is proposed fly as a Pioneers hosted payload aboard one of NASA's Commercial Lunar Payload Services (CLPS) landers, to deliver an optical interferometer to the lunar surface. The combination of high spatial resolution from optical interferometry, with deep sensitivity from the stability of the lunar surface, would open up unprecedented discovery space. After landing on the lunar surface, the CLPS rover will deploy the pre-loaded MoonLITE outboard optical element 100 meters from the lander, establishing a interferometric observatory with a single deployment. MoonLITE combines a 110 microarcsecond limiting spatial resolution with enough sensitivity to observe targets fainter than 17th magnitude in the visible. The capabilities of MoonLITE open a unique discovery space that includes direct size measurements of the smallest, coolest stars and substellar brown dwarfs; searches for close-in stellar companions orbiting exoplanet-hosting stars that could confound our understanding and characterization of the frequency of earth-like planets; direct size measurements of young stellar objects and characterization of the terrestrial planet forming regions of these young stars; measurements of the inner regions and binary fraction of active galactic nuclei; and probing the very nature of spacetime foam itself. Twenty percent of the observing time of this revolutionary observatory will be also made available to the broader community via a guest observer program. MoonLITE takes advantage of the CLPS opportunity to place an interferometer in space, on a stable lunar surface, and delivers an unprecedented combination of sensitivity and angular resolution, at the remarkably affordable cost point of Pioneers.
  50. Chabot, N., Rivkin, A., Cheng, A., et al., (including Moskovitz, N.), 2024, PSJ, 5, 49, Achievement of the Planetary Defense Investigations of the Double Asteroid Redirection Test (DART) Mission
    NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earth-based observations showed that the binary orbital period was changed by 33.24 minutes, with two independent analysis methods each reporting a 1 uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, , resulting from DART's kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DART's investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DART's successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DART's kinetic impact test and the Didymos system will continue. In particular, ESA's Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the DidymosDimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense.
  51. Weaver, H., Sunshine, J., Ernst, C., et al., (including Moskovitz, N.), 2024, PSJ, 5, 43, Lucy Observations of the DART Impact Event
    The Lucy LOng Range Reconnaissance Imager (L'LORRI) took 1549 images of the DidymosDimorphos binary system, starting 12 hr before the Double Asteroid Redirection Test (DART) impact event on 2022 September 26 and ending 24 hr after it. The Lucy imaging campaign provided pre-impact monitoring of the baseline brightness of the Didymos system, as well as intensive 1 s cadence imaging starting 3 minutes prior to impact and extending until 4 minutes after impact, and then continued monitoring at increasing cadences and image exposure times to measure the Didymos system brightness changes produced by ejecta released during the impact. One of the L'LORRI images encompassed the exact time when the DART spacecraft impacted Dimorphos, but there is no evidence of a thermally generated optical flash in the image. L'LORRI observed a shell of fast-moving ejecta, and we derive a range of projected speeds (0.263.6 km s1) for that material. The much slower moving ejecta (1 m s1) stayed within a single L'LORRI pixel for the entire duration of the Lucy-DART program. We find that the slow ejecta were responsible for 57.4% 2.2% of the total post-impact brightness increase measured by L'LORRI, while the fast ejecta were responsible for 42.6% 2.3% of the post-impact brightness increase. The initial brightness increase relative to the pre-impact Didymos system brightness was significantly smaller for L'LORRI compared to that measured by some ground-based observers, which is plausibly explained by differences in phase angles and different responses to sodium emission depending on the camera spectral bandwidths.
  52. Devogele, M., McGilvray, A., MacLennan, E., et al., (including Kareta, T., Skiff, B.), 2024, PSJ, 5, 44, Surface Heterogeneity, Physical, and Shape Model of Near-Earth Asteroid (52768) 1998 OR2
    On 2020 April 29, the near-Earth object (52768) 1998 OR2 experienced a close approach to Earth at a distance of 16.4 lunar distances (LD). 1998 OR2 is a potentially hazardous asteroid of absolute magnitude H = 16.04 that can currently come as close to Earth as 3.4 LD. We report here observations of this object in polarimetry, photometry, and radar. Our observations show that the physical characteristics of 1998 OR2 are similar to those of both M- and S-type asteroids. Arecibo's radar observations provide a high radar albedo of ${\hat{\sigma }}_{\mathrm{OC}}\,=$ 0.29 0.08, suggesting that metals are present in 1998 OR2 near-surface. We find a circular polarization ratio of c = 0.291 0.012, and the delay-Doppler images show that the surface of 1998 OR2 is a top-shape asteroid with large-scale structures such as large craters and concavities. The polarimetric observations display a consistent variation of the polarimetric response as a function of the rotational phase, suggesting that the surface of 1998 OR2 is heterogeneous. Color observations suggest an X-complex taxonomy in the BusDeMeo classification. Combining optical polarization, radar, and two epochs from the NEOWISE satellite observations, we derived an equivalent diameter of D = 1.80 0.1 km and a visual albedo p v = 0.21 0.02. Photometric and radar data provide a sidereal rotation period of P = 4.10872 0.00001 hr, a pole orientation of (332.3 5, 20.7 5), and a shape model with dimensions of

    $({2.08}_{-0.10}^{+0.10},{1.93}_{-0.10}^{+0.10},{1.60}_{-0.05}^{+0.05})$ km.

  53. Bourdelle de Micas, J., Fornasier, S., Delbo, M., et al., (including van Belle, G.), 2024, A&A, 682, A64, Compositional characterization of a primordial S-type asteroid family of the inner main belt
    Context. Recently, a primordial family of moderate-albedo asteroid fragments was discovered in the inner main belt. Its age was estimated to be 4.4 1.7 Gyr. However, there is a lack of compositional characterization, which is important to the study of the earliest collisions in the main belt.
    Aims: In addition to the previously identified members and the parameters that define the family's borders (V shape), we expanded the list of family members to include asteroids located within the central region of the V shape. These additional potential members were selected based on their diameter (larger than 7 km) and their geometric visible albedo (greater than or equal to 12%). Subsequently, we conducted a spectroscopic survey to determine the dominant taxonomy and composition of this family. This allowed us to further refine the list of family members by removing interlopers.
    Methods: From an initial list of 263 asteroids that are considered to be potential members of the aforementioned primordial family, we retrieved their spectra in the visible and near-infrared range from the literature and from the Gala DR3 spectral catalog of Solar System objects. For asteroids with no or poor signal-to-noise ratio spectra in the literature, we carried out new ground-based observations. We obtained new spectra for 33 members of the family using the 1.82 m Asiago Telescope for the visible spectroscopy, while for near-infrared spectroscopy, we used the 3.58 m Telescopio Nazionale Galileo (TNG) and the 4.30 m Lowell Discovery Telescope (LDT).
    Results: In total, we collected spectra for 261 potential members of the primordial S-type family out of 263. We determined their spectral taxonomy and properties, such as spectral slopes and absorption band parameters, when existing. Using the taxonomical characterization and the orbital space parameters, we identified and removed 71 interlopers from the potential members list. The final list of the primordial S-type family members includes 190 asteroids. The family is dominated by S-complex (~71%) asteroids with a mineralogy similar to ordinary chondrites and pyroxene-rich minerals. The family also contains members classified as L-types and V-types. (~15% and ~9%, respectively).
    Conclusions: The mean albedo of the family is ~23%, and its largest probable remnant is the asteroid (30) Urania. The estimated size of the family parent body ranges between 110 and 210 km. This size range is compatible with the progenitor of H and L chondrites.

    New spectra are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/682/A64

  54. Carleton, T., Ellsworth-Bowers, T., Windhorst, R., et al., (including Archer, H.), 2024, ApJL, 961, L37, PEARLS: A Potentially Isolated Quiescent Dwarf Galaxy with a Tip of the Red Giant Branch Distance of 30 Mpc
    A wealth of observations have long suggested that the vast majority of isolated classical dwarf galaxies (M * = 107109 M ) are currently star forming. However, recent observations of the large abundance of "ultra-diffuse galaxies" beyond the reach of previous large spectroscopic surveys suggest that our understanding of the dwarf galaxy population may be incomplete. Here we report the serendipitous discovery of an isolated quiescent dwarf galaxy in the nearby Universe, which was imaged as part of the JWST PEARLS Guaranteed Time Observation program. Remarkably, individual red-giant branch stars are visible in this near-IR imaging, suggesting a distance of 30 4 Mpc, and a wealth of archival photometry point to an sSFR of 2 1011 yr1 and star formation rate of 4 104 M yr1. Spectra obtained with the Lowell Discovery Telescope find a recessional velocity consistent with the Hubble Flow and >1500 km s1 separated from the nearest massive galaxy in Sloan Digital Sky Survey suggesting that this galaxy was either quenched from internal mechanisms or had a very high-velocity (1000 km s1) interaction with a nearby massive galaxy in the past. This analysis highlights the possibility that many nearby quiescent dwarf galaxies are waiting to be discovered and that JWST has the potential to resolve them.
  55. Tegler, S., Grundy, W., Loeffler, M., et al., (including Hanley, J.), 2024, PSJ, 5, 31, Optical Constants of Ices Important to Planetary Science from Laboratory Reflectance Spectroscopy
    Laboratory-derived optical constants are essential for identifying ices and measuring their relative abundances on solar system objects. Almost all optical constants of ices important to planetary science come from experiments with transmission geometries. Here we describe our new experimental setup and the modification of an iterative algorithm in the literature to measure the optical constants of ices from experiments with reflectance geometries. We apply our techniques to CH4 ice and H2O ice samples and find good agreement between our values and those in the literature, except for one CH4 band in the literature that likely suffers from saturation. The work we present here demonstrates that labs with reflectance geometries can generate optical constants essential for the proper analysis of near- and mid-infrared spectra of outer solar system objects such as those obtained with the James Webb Space Telescope.
  56. Moskovitz, N., Thomas, C., Pravec, P., et al., (including Polakis, T., Kareta, T., Skiff, B., Burt, B., Thirouin, A.), 2024, PSJ, 5, 35, Photometry of the Didymos System across the DART Impact Apparition
    On 2022 September 26, the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos. This demonstrated the efficacy of a kinetic impactor for planetary defense by changing the orbital period of Dimorphos by 33 minutes. Measuring the period change relied heavily on a coordinated campaign of lightcurve photometry designed to detect mutual events (occultations and eclipses) as a direct probe of the satellite's orbital period. A total of 28 telescopes contributed 224 individual lightcurves during the impact apparition from 2022 July to 2023 February. We focus here on decomposable lightcurves, i.e., those from which mutual events could be extracted. We describe our process of lightcurve decomposition and use that to release the full data set for future analysis. We leverage these data to place constraints on the postimpact evolution of ejecta. The measured depths of mutual events relative to models showed that the ejecta became optically thin within the first 1 day after impact and then faded with a decay time of about 25 days. The bulk magnitude of the system showed that ejecta no longer contributed measurable brightness enhancement after about 20 days postimpact. This bulk photometric behavior was not well represented by an HG photometric model. An HG 1 G 2 model did fit the data well across a wide range of phase angles. Lastly, we note the presence of an ejecta tail through at least 2023 March. Its persistence implied ongoing escape of ejecta from the system many months after DART impact.
  57. Doner, A., Horanyi, M., Bagenal, F., et al., (including Grundy, W.), 2024, ApJL, 961, L38, New Horizons Venetia Burney Student Dust Counter Observes Higher than Expected Fluxes Approaching 60 au
    The NASA New Horizons Venetia Burney Student Dust Counter (SDC) measures dust particle impacts along the spacecraft's flight path for grains with mass 1012 g, mapping out their spatial density distribution. We present the latest SDC dust density, size distribution, and flux measurements through 55 au and compare them to numerical model predictions. Kuiper Belt objects (KBOs) are thought to be the dominant source of interplanetary dust particles in the outer solar system due to both collisions between KBOs and their continual bombardment by interstellar dust particles. Continued measurements through 55 au show higher than model-predicted dust fluxes as New Horizons approaches the putative outer edge of the Kuiper Belt (KB). We discuss potential explanations for the growing deviation: radiation pressure stretches the dust distribution to further heliocentric distances than its parent body distribution; icy dust grains undergo photosputtering that rapidly increases their response to radiation pressure forces and pushes them further away from the Sun; and the distribution of KBOs may extend much further than existing observations suggest. Ongoing SDC measurements at even larger heliocentric distances will continue to constrain the contributions of dust production in the KB. Continued SDC measurements remain crucial for understanding the Kuiper Belt and the interpretation of dust disks around other stars.
  58. Clark, C., van Belle, G., Horch, E., et al., (including von Braun, K., Llama, J.), 2024, AJ, 167, 56, The POKEMON Speckle Survey of Nearby M Dwarfs. II. Observations of 1125 Targets
    Stellar multiplicity is correlated with many stellar properties, yet multiplicity measurements have proven difficult for the M dwarfs-the most common type of star in our galaxy-due to their faintness and the fact that a reasonably complete inventory of later M dwarfs did not exist until recently. We have therefore carried out the Pervasive Overview of "Kompanions" of Every M dwarf in Our Neighborhood (POKEMON) survey, which made use of the Differential Speckle Survey Instrument on the 4.3 m Lowell Discovery Telescope, along with the NN-EXPLORE Exoplanet Stellar Speckle Imager on the 3.5 m WIYN telescope. The POKEMON sample is volume limited from M0V through M9V out to 15 pc, with additional brighter targets at larger distances. In total, 1125 targets were observed. New discoveries were presented in the first paper in the series. In this second paper in the series, we present all detected companions, gauge our astrometric and photometric precision, and compare our filtered and filterless speckle observations. We find that the majority (58.9%) of the companions we detect in our speckle images are not resolved in Gaia, demonstrating the need for high-resolution imaging in addition to long-term astrometric monitoring. Additionally, we find that the majority (73.2%) of simulated stellar companions would be detectable by our speckle observations. Specifically within 100 au, we find that 70.3% of simulated companions are recovered. Finally, we discuss future directions of the POKEMON survey.
  59. McNanna, M., Bechtol, K., Mau, S., et al., (including Kuehn, K.), 2024, ApJ, 961, 126, A Search for Faint Resolved Galaxies Beyond the Milky Way in DES Year 6: A New Faint, Diffuse Dwarf Satellite of NGC 55
    We report results from a systematic wide-area search for faint dwarf galaxies at heliocentric distances from 0.3 to 2 Mpc using the full 6 yr of data from the Dark Energy Survey (DES). Unlike previous searches over the DES data, this search specifically targeted a field population of faint galaxies located beyond the Milky Way virial radius. We derive our detection efficiency for faint, resolved dwarf galaxies in the Local Volume with a set of synthetic galaxies and expect our search to be complete to M V (7, 10) mag for galaxies at D = (0.3, 2.0) Mpc. We find no new field dwarfs in the DES footprint, but we report the discovery of one high-significance candidate dwarf galaxy at a distance of ${2.2}_{-0.12}^{+0.05}\,\mathrm{Mpc}$ , a potential satellite of the Local Volume galaxy NGC 55, separated by 47' (physical separation as small as 30 kpc). We estimate this dwarf galaxy to have an absolute V-band magnitude of $-{8.0}_{-0.3}^{+0.5}\,\mathrm{mag}$ and an azimuthally averaged physical half-light radius of ${2.2}_{-0.4}^{+0.5}\,\mathrm{kpc}$ , making this one of the lowest surface brightness galaxies ever found with $\mu =32.3\,\mathrm{mag}\,{\mathrm{arcsec}}^{-2}$ . This is the largest, most diffuse galaxy known at this luminosity, suggesting possible tidal interactions with its host.
  60. Souza-Feliciano, A., Holler, B., Pinilla-Alonso, N., et al., (including Stansberry, J.), 2024, A&A, 681, L17, Spectroscopy of the binary TNO Mors-Somnus with the JWST and its relationship to the cold classical and plutino subpopulations observed in the DiSCo-TNO project
    Context. Trans-Neptunian objects (TNOs) are remnants of small icy bodies from planetary formation that orbit in the region beyond Neptune. Within the population of TNOs, Trans-Neptunian binaries (TNBs) provide a valuable opportunity to test the models of the formation and evolution of planetesimals in the trans-Neptunian region. Various theories have been proposed to describe the observed separations between binary components, their relative sizes, and other orbital parameters. The colors of TNOs have been used to trace the dynamical history of the outer Solar System and the colors of TNB components provide tests for formation theories. However, spectral information for the components of small TNBs, crucial information that could validate formation mechanisms, has until now remained elusive.
    Aims: The main goal of this work is to characterize the near-infrared spectral properties of the TNB plutino (341520) Mors-Somnus, the only TNB with resolved components in the James Webb Space Telescope (JWST) Large Cycle 1 General Observer program "DiSCo-TNOs" (PID 2418; PI: Pinilla-Alonso). The secondary goal is to use the surface compositions of the individual components of the Mors-Somnus system to probe formation and dynamical evolution in the outer Solar System through comparison to the surface properties of the cold classical and plutino (3:2 resonant) dynamical groups.
    Methods: To achieve these goals, we measured the spectral slope of the continuum and identified absorption bands in the individual spectra of Mors and Somnus, as well as in those of the cold classicals and plutinos obtained with the NIRSpec Integral Field Unit (IFU) and the PRISM/CLEAR disperser (0.6-5.3 m), and compared these results to shed light on the dynamical evolution of the Mors-Somnus binary.
    Results: The spectra of Mors and Somnus are similar and indicate the presence of complex organic materials, CO2, CO, OH-compounds, and tentative nitrogen-rich materials. We find a high degree of compositional diversity in the plutino population, a group of TNOs that likely formed elsewhere and moved to their current orbits during the migration of Neptune, while the cold classical TNOs, which likely formed in situ, appear more homogeneous.
    Conclusions: The very wide separation between the components, their nearly equal sizes, and the high orbital inclination of the system suggest this plutino binary is a survivor of the primordial population of objects beyond 30 au. The similarities found between the spectral features of the plutinos Mors and Somnus and those of all of the cold classical TNOs in the DiSCo-TNOs sample as well as the high degree of compositional heterogeneity found in the plutino population provide compositional evidence for evaluation of Neptune's migration in the trans-Neptunian region early on in the history of the Solar System.
  61. Scheirich, P., Pravec, P., Meyer, A., et al., (including Moskovitz, N.), 2024, PSJ, 5, 17, Dimorphos Orbit Determination from Mutual Events Photometry
    The NASA Double Asteroid Redirection Test spacecraft successfully impacted the DidymosDimorphos binary asteroid system on 2022 September 26 UTC. We provide an update to its preimpact mutual orbit and estimate the postimpact physical and orbital parameters, derived using ground-based photometric observations taken from 2022 July to 2023 February. We found that the total change of the orbital period was 33.240 0.072 minutes (all uncertainties are 3). We obtained the eccentricity of the postimpact orbit to be 0.028 0.016 and the apsidal precession rate was 7.3 2.0 degrees day1 from the impact to 2022 December 2. The data taken later in 2022 December to 2023 February suggest that the eccentricity dropped close to zero or the orbit became chaotic approximately 70 days after the impact. Most of the period change took place immediately after the impact, but in the few weeks following the impact it was followed by an additional change of $-{27}_{-58}^{+19}$ s or 19 18 s (the two values depend on the approach we used to describe the evolution of the orbital period after the impactan exponentially decreasing angular acceleration or the assumption of a constant orbital period, which changed abruptly some time after the impact, respectively). We estimate the preimpact DimorphosDidymos size ratio was 0.223 0.012 and the postimpact is 0.202 0.018, which indicate a marginally significant reduction of Dimorphos' volume by (9 9)% as the result of the impact.
  62. Marques, G., Madhavacheril, M., Darwish, O., et al., (including Kuehn, K.), 2024, JCAP, 2024, 033, Cosmological constraints from the tomography of DES-Y3 galaxies with CMB lensing from ACT DR4
    We present a measurement of the cross-correlation between the MAGLIM galaxies selected from the Dark Energy Survey (DES) first three years of observations (Y3) and cosmic microwave background (CMB) lensing from the Atacama Cosmology Telescope (ACT) Data Release 4 (DR4), reconstructed over ~ 436 deg2 of the sky. Our galaxy sample, which covers ~ 4143 deg2, is divided into six redshift bins spanning the redshift range of 0.20<z<1.05. We adopt a blinding procedure until passing all consistency and systematics tests. After imposing scale cuts for the cross-power spectrum measurement, we reject the null hypothesis of no correlation at 9.1. We constrain cosmological parameters from a joint analysis of galaxy and CMB lensing-galaxy power spectra considering a flat CDM model, marginalized over 23 astrophysical and systematic nuisance parameters. We find the clustering amplitude S 8 8( m /0.3)0.5 = 0.75+0.04 -0.05. In addition, we constrain the linear growth of cosmic structure as a function of redshift. Our results are consistent with recent DES Y3 analyses and suggest a preference for a lower S 8 compared to results from measurements of CMB anisotropies by the Planck satellite, although at a mild level (< 2) of statistical significance.
  63. Bom, C., Annis, J., Garcia, A., et al., (including Kuehn, K.), 2024, ApJ, 960, 122, Designing an Optimal Kilonova Search Using DECam for Gravitational-wave Events
    We address the problem of optimally identifying all kilonovae detected via gravitational-wave emission in the upcoming LIGO/Virgo/KAGRA observing run, O4, which is expected to be sensitive to a factor of ~7 more binary neutron star (BNS) alerts than previously. Electromagnetic follow-up of all but the brightest of these new events will require >1 m telescopes, for which limited time is available. We present an optimized observing strategy for the DECam during O4. We base our study on simulations of gravitational-wave events expected for O4 and wide-prior kilonova simulations. We derive the detectabilities of events for realistic observing conditions. We optimize our strategy for confirming a kilonova while minimizing telescope time. For a wide range of kilonova parameters, corresponding to a fainter kilonova compared to GW170817/AT 2017gfo, we find that, with this optimal strategy, the discovery probability for electromagnetic counterparts with the DECam is ~80% at the nominal BNS gravitational-wave detection limit for O4 (190 Mpc), which corresponds to an ~30% improvement compared to the strategy adopted during the previous observing run. For more distant events (~330 Mpc), we reach an ~60% probability of detection, a factor of ~2 increase. For a brighter kilonova model dominated by the blue component that reproduces the observations of GW170817/AT 2017gfo, we find that we can reach ~90% probability of detection out to 330 Mpc, representing an increase of ~20%, while also reducing the total telescope time required to follow up events by ~20%.
  64. Deming, D., Llama, J., Fu, G., 2024, AJ, 167, 34, Precise Radial Velocities Using Line Bisectors
    We study the properties of line bisectors in the spectrum of the Sun-as-a-star, as observed using the Integrated Sunlight Spectrometer (ISS) of the SOLIS project. Our motivation is to determine whether changes in line shape due to magnetic modulation of photospheric convection can be separated from the 9 cm s-1 Doppler reflex of the Earth's orbit. Measuring bisectors of 21 lines over a full solar cycle, our results overwhelmingly indicate that solar magnetic activity modulates photospheric convection so as to reduce the asymmetries of line profiles in the spectrum of the Sun-as-a-star (having both C-shaped and reversed-C-shaped bisectors). However, some lines are constant or have variations in shape that are too small to measure. We inject a 9 cm s-1 radial velocity signal with a 1 yr period into the ISS spectra. Informed by a principal component analysis of the bisectors, we fit the most significant components to the bisectors of each line by linear regression, including a zero-point offset in velocity that is intended to capture the injected radial velocity signal. Averaging over lines, we are able to recover that signal to solid statistical significance in the presence of much larger changes in the line shapes. Although our work has limitations (that we discuss), we establish that changes in absorption line shapes do not in themselves prevent the detection of an Earth-like planet orbiting a Sun-like star using precise radial velocity techniques.
  65. Anbajagane, D., Chang, C., Baxter, E., et al., (including Kuehn, K.), 2024, MNRAS, 527, 9378, Cosmological shocks around galaxy clusters: a coherent investigation with DES, SPT, and ACT
    We search for signatures of cosmological shocks in gas pressure profiles of galaxy clusters using the cluster catalogues from three surveys: the Dark Energy Survey (DES) Year 3, the South Pole Telescope (SPT) SZ survey, and the Atacama Cosmology Telescope (ACT) data releases 4, 5, and 6, and using thermal Sunyaev-Zeldovich (SZ) maps from SPT and ACT. The combined cluster sample contains around 105 clusters with mass and redshift ranges $10^{13.7} \lt M_{\rm 200m}/\, {\rm M}_\odot \lt 10^{15.5}$ and 0.1 < z < 2, and the total sky coverage of the maps is $\approx 15\, 000 \deg ^2$. We find a clear pressure deficit at R/R200m 1.1 in SZ profiles around both ACT and SPT clusters, estimated at 6 significance, which is qualitatively consistent with a shock-induced thermal non-equilibrium between electrons and ions. The feature is not as clearly determined in profiles around DES clusters. We verify that measurements using SPT or ACT maps are consistent across all scales, including in the deficit feature. The SZ profiles of optically selected and SZ-selected clusters are also consistent for higher mass clusters. Those of less massive, optically selected clusters are suppressed on small scales by factors of 2-5 compared to predictions, and we discuss possible interpretations of this behaviour. An oriented stacking of clusters - where the orientation is inferred from the SZ image, the brightest cluster galaxy, or the surrounding large-scale structure measured using galaxy catalogues - shows the normalization of the one-halo and two-halo terms vary with orientation. Finally, the location of the pressure deficit feature is statistically consistent with existing estimates of the splashback radius.
  66. Carruba, V., Camargo, J., Aljbaae, S., et al., (including Kuehn, K.), 2024, MNRAS, 527, 6495, Main belt asteroids taxonomical information from dark energy survey data
    While proper orbital elements are currently available for more than 1 million asteroids, taxonomical information is still lagging behind. Surveys like SDSS-MOC4 provided preliminary information for more than 100 000 objects, but many asteroids still lack even a basic taxonomy. In this study, we use Dark Energy Survey (DES) data to provide new information on asteroid physical properties. By cross-correlating the new DES data base with other data bases, we investigate how asteroid taxonomy is reflected in DES data. While the resolution of DES data is not sufficient to distinguish between different asteroid taxonomies within the complexes, except for V-type objects, it can provide information on whether an asteroid belongs to the C- or S-complex. Here, machine learning methods optimized through the use of genetic algorithms were used to predict the labels of more than 68 000 asteroids with no prior taxonomic information. Using a high-quality, limited set of asteroids with data on gri slopes and i - z colours, we detected 409 new possible V-type asteroids. Their orbital distribution is highly consistent with that of other known V-type objects.
  67. Gatti, M., Jeffrey, N., Whiteway, L., et al., (including Kuehn, K.), 2024, MNRAS, 527, L115, Detection of the significant impact of source clustering on higher order statistics with DES Year 3 weak gravitational lensing data
    We measure the impact of source galaxy clustering on higher order summary statistics of weak gravitational lensing data. By comparing simulated data with galaxies that either trace or do not trace the underlying density field, we show that this effect can exceed measurement uncertainties for common higher order statistics for certain analysis choices. We evaluate the impact on different weak lensing observables, finding that third moments and wavelet phase harmonics are more affected than peak count statistics. Using Dark Energy Survey (DES) Year 3 (Y3) data, we construct null tests for the source-clustering-free case, finding a p-value of p = 4 10-3 (2.6) using third-order map moments and p = 3 10-11 (6.5) using wavelet phase harmonics. The impact of source clustering on cosmological inference can be either included in the model or minimized through ad hoc procedures (e.g. scale cuts). We verify that the procedures adopted in existing DES Y3 cosmological analyses were sufficient to render this effect negligible. Failing to account for source clustering can significantly impact cosmological inference from higher order gravitational lensing statistics, e.g. higher order N-point functions, wavelet-moment observables, and deep learning or field-level summary statistics of weak lensing maps.
  68. Giannini, G., Alarcon, A., Gatti, M., et al., (including Kuehn, K.), 2024, MNRAS, 527, 2010, Dark Energy Survey Year 3 results: redshift calibration of the MAGLIM lens sample from the combination of SOMPZ and clustering and its impact on cosmology
    We present an alternative calibration of the MAGLIM lens sample redshift distributions from the Dark Energy Survey (DES) first 3 yr of data (Y3). The new calibration is based on a combination of a self-organizing-map-based scheme and clustering redshifts to estimate redshift distributions and inherent uncertainties, which is expected to be more accurate than the original DES Y3 redshift calibration of the lens sample. We describe in detail the methodology, and validate it on simulations and discuss the main effects dominating our error budget. The new calibration is in fair agreement with the fiducial DES Y3 n(z) calibration, with only mild differences (<3) in the means and widths of the distributions. We study the impact of this new calibration on cosmological constraints, analysing DES Y3 galaxy clustering and galaxy-galaxy lensing measurements, assuming a Lambda cold dark matter cosmology. We obtain m = 0.30 0.04, 8 = 0.81 0.07, and S8 = 0.81 0.04, which implies a ~0.4 shift in the - S8 plane compared to the fiducial DES Y3 results, highlighting the importance of the redshift calibration of the lens sample in multiprobe cosmological analyses.

    69. 68 publications and 108 citations in 2024.

68 publications and 108 citations total.

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