AAS 201st Meeting, January, 2003
Session 20. Star Formation I
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[20.06] Accretion and Outflow Signatures Observed in a Weak-Lined T Tauri Star? The Special Case of KH 15D

C.M. Hamilton (Wesleyan U./Connecticut College), W. Herbst (Wesleyan University), C.A.L. Bailer-Jones (MPIA - Heidelberg), R. Mundt (MPIA- Heidelberg)

We present high resolution spectra (R ~ 40,000) of the unique pre-main sequence eclipsing object KH 15D. These spectra cover the wavelength range from 4780 to 6810 Å and were obtained with the Very Large Telescope (VLT) of the European Southern Observatory as a part of the international campaign to monitor KH 15D during its December 2001 eclipse. In particular, spectra were taken just prior to eclipse, just after mid-eclipse, and during egress. These show that while the star is eclipsed, the spectrum is an attenuated version of the bright state. However, during eclipse and egress, the spectrum makes a transition from that of a "weak-lined" T Tauri star (WTTS) with an H\alpha equivalent width of ~ 2 Å, to one that is more characteristic of a "classical" T Tauri star (CTTS) with H\alpha equivalent widths ranging from ~ 30 Å to ~ 50 Å respectively. There is preliminary evidence for outflow activity in the [OI] \lambda\lambda 6300, 6363 and the [SII] \lambda\lambda 6716, 6731 lines. These profiles, in addition to the H\alpha (and H\beta) profiles, seem to indicate that KH 15D is still undergoing accretion from a circumstellar disk. It has been generally assumed that WTTSs are no longer accreting and that their H-alpha emission can be attributed to the magnetic activity of the underlying star. It would appear that the fortuitous geometry of this eclipsing system is showing us that at least one WTTS is in fact, still undergoing accretion.

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

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