AAS 205th Meeting, 9-13 January 2005
Session 156 T Tauri Stars and Their Disks
Oral, Thursday, January 13, 2005, 10:00-11:30am, California

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[156.04] Molecular Hydrogen and Lyman-alpha Emission in FUV Spectra of CTTSs

Gregory J. Herczeg, J. L. Linsky, B. E. Wood (JILA/University of Colorado), F. M. Walter, J. Valenti (SUNY - Stony Brook), C. M. Johns-Krull (STScI)

The presence and structure of gas in circumstellar disks around young stars has profound implications on the formation and early evolution of planets. We use HST/STIS and FUSE spectra of a small sample of CTTSs to study fluorescent H2 emission, pumped by Lyman-alpha. We find that the H2 traces 2500 K gas at or near the disk surface within 2 AU of the central star. These H2 lines allow us to indirectly measure Lyman-alpha emission, which is typically obscured by H I absorption in our line of sight to the star. Lyman-alpha emission contributes 80-90% of the total FUV emission from CTTSs, and alters the disk chemistry.

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

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© 2004. The American Astronomical Society.