POSTER PAPER 3.04

FUSE Observations of Molecular Hydrogen in PMS Stars
Gregory J. Herczeg, Jeffrey L. Linsky, Alexander Brown, Graham M. Harper, & Erik Wilkinson

Institute: JILA/University of Colorado & N.I.S.T.
Institute: CASA/University of Colorado
Contact Email: gregoryh@casa.colorado.edu

Abstract: Pre-main sequence stars exhibit rich molecular hydrogen emission and absorption spectra in the FUV. We survey four PMS stars that have been observed with FUSE: the Classical T Tauri Stars TW Hya and V4046 Sgr, and the Herbig Ae/Be stars AB Aur and DX Cha. The spectrum of TW Hya and V4046 Sgr show H2 fluorescence in Lyman (B-X) and Werner (C-X) bands caused by photoexcitation by Lyman alpha, H2 absorption occurs against line and continuum emission in the spectrum of AB Aur and DX Cha. We measure column densities of log(NH2)=20.2 +/- 0.2 cm-2 towards AB Aur and log(NH2)=19.4 +/- 0.2 cm-2 towards DX Cha. The rotational excitation temperature of the H2 gas around DX Cha varies from 300--500 K for different rotational levels, compared with 65--450 K the gas around AB Aur. We discuss the circumstellar origin of H2 emission and absorption.

FUSE Observations of Molecular Hydrogen in PMS Stars [PDF - Type 1 fonts]

FUSE Observations of Molecular Hydrogen in PMS Stars [PS]

Index Keywords: CTTSs; Herbig Ae/Be; Star Formation; Circumstellar Disks; H2; FUSE

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Manuscript submitted: 2001-Sep-25
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown, G. M. Harper, & T. R. Ayres. Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems, & The Sun,
© 2003 University of Colorado.