AAS 202nd Meeting, May 2003
Session 24 When Do Planets Form?
Topical Oral, Tuesday, May 27, 2003, 8:30-10:00am and 10:45am-12:30pm, 204

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[24.08] X-rays from T Tauri Stars: Probing Star-Disk Interactions

J.H. Kastner (Center for Imaging Science, Rochester Institute of Technology), D.A. Weintraub (Dept. of Physics & Astronomy, Vanderbilt U.), D.P. Huenemoerder, N.S. Schulz (MIT Center for Space Research)

The origin of the X-rays from young stars is still a subject of considerable debate. While it had been thought that stellar magnetic dynamos driven by rapid rotation are ultimately responsible for the production of X-rays from T Tauri stars (TTS), recent evidence to the contrary has led to new speculation concerning alternative mechanisms. We have been exploring whether there is observational evidence that X-rays from T Tauri stars are due to interactions between stars and circumstellar disks and, hence, are diagnostic of the presence (or absence) of such disks. Archival ROSAT data demonstrates that the X-ray spectrum of a low-mass star softens as the star evolves from the T Tauri phase to the main sequence. It is unclear whether this trend can be attributed to age-dependent changes in intrinsic X-ray spectrum, to a decrease in the column density of circumstellar gas (e.g., in residual protoplanetary disks), or to the diminishing contributions of star-disk interactions to X-ray emission. New results from high-resolution spectroscopy of TW Hya --- the only classical TTS for which such data have been obtained thus far --- appear to favor the last interpretation. These results from Chandra and XMM-Newton X-ray gratings spectroscopy provide evidence that the bulk of the X-ray emission from TW Hya is generated via mass accretion from its circumstellar disk. Additional high-resolution X-ray spectra of nearby T Tauri stars will provide tests of this hypothesis.

The author(s) of this abstract have provided an email address for comments about the abstract: jhk@cis.rit.edu

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© 2003. The American Astronomical Soceity.