Name/Affiliation: David Principe (Rochester Institute of Technology)
Magnetic Activity and Accretion in Three Nearby, Nearly Edge-on Pre-MS Star-disk Systems
We investigate, via contemporaneous X-ray and optical/IR observations, the nearby, pre-main sequence star/disk systems T Chamaeleontis (T Cha; D ~ 110 pc, age 3-5 Myr) and TWA 30A and 30B (D ~ 40 pc; age ~ 8 Myr). All three of these systems present opportunities to probe pre-main sequence (pre-MS) star-disk interactions during late-stage circumstellar disk evolution. The classical T Tauri star T Cha is the closest known example of a nearly edge-on, actively accreting, solar-mass star/disk system; furthermore, T Cha may be orbited by a low-mass companion or massive planet that has cleared an inner hole in its disk. We analyze near-simultaneous Chandra high-resolution X-ray and optical H-alpha spectroscopy observations of T Cha to search for correlations between X-ray and optical emission signatures of accretion, and to infer the X-ray absorbing properties of the T Cha circumstellar disk. We also present contemporaneous XMM-Newton X-ray and optical/IR spectroscopic observations of the nearby, actively accreting, very low-mass (mid-M) pre-MS star/disk/jet systems TWA 30A and 30B. Like T Cha, each component of this wide binary is viewed through a nearly edge-on circumstellar disk. Both TWA 30A and 30B display large near-IR variability, suggestive of (respectively) variable obscuration of the stellar photosphere and a possible disk-rim warp. The proximity and edge-on viewing geometries of the TWA 30 pair afford a unique opportunity to investigate the composition of circumstellar disks orbiting pre-MS stars near the H-burning limit. We investigate potential X-ray accretion signatures, and compare the levels of magnetic activity in TWA 30A and 30B to those of other nearby, low-mass pre-MS stars.