The Origins of Fluorescent H_2 Emission From T Tauri Stars
Abstract
We survey fluorescent H_2 emission in HST STIS spectra of the classical T Tauri stars (CTTSs) TW Hya, DF Tau, RU Lupi, T Tau, and DG Tau, and the weak-lined T Tauri star (WTTS) V836 Tau. From each of those sources we detect between 41 and 209 narrow H_2 emission lines, most of which are pumped by strong Lyα emission. H_2 emission is not detected from the WTTS V410 Tau. The fluorescent H_2 emission appears to be common to circumstellar environments around all CTTSs, but high spectral and spatial resolution STIS observations reveal diverse phenomenon. Blueshifted H_2 emission detected from RU Lupi, T Tau, and DG Tau is consistent with an origin in an outflow. The H_2 emission from TW Hya, DF Tau, and V836 Tau is centered at the radial velocity of the star and is consistent with an origin in a warm disk surface. The H_2 lines from RU Lupi, DF Tau, and T Tau also have excess blueshifted H_2 emission that extends to as much as -100 km s^(-1). The strength of this blueshifted component from DF Tau and T Tau depends on the upper level of the transition. In all cases, the small aperture and attenuation of H_2 emission by stellar winds restricts the H_2 emission to be formed close to the star. In the observation of RU Lupi, the Lyα emission and the H_2 emission that is blueshifted by 15 km s^(-1) are extended to the SW by ~0".07, although the faster H_2 gas that extends to ~100 km s^(-1) is not spatially extended. We also find a small reservoir of H_2 emission from TW Hya and DF Tau consistent with an excitation temperature of ~2.5 × 10^4 K.
Additional Information
© 2006 American Astronomical Society. Received 2005 November 2; accepted 2006 February 16. This research was funded in part by STScI programs GTO-7718, GTO-8041, and GO-8157 to the University of Colorado and to SUNY Stony Brook, and by the Swedish National Space Board. This paper is based on observations made by the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This research was also funded in part by the STScI program AR-9930 to the University of Colorado and by NASA program S-56500-D to the University of Colorado. We thank the anonymous referee for valuable suggestions. We also thank Ilya Ilyin, who obtained our NOT observations and reduced the spectrograms. G. J. H. thanks Carol Grady for valuable discussion concerning the spatial distribution of emission from several other CTTSs, and Gail Schaefer for valuable discussion regarding the position of DF Tau in the aperture.Attached Files
Published - HERapjss06.pdf
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Additional details
- Eprint ID
- 23876
- Resolver ID
- CaltechAUTHORS:20110602-110356928
- GTO-7718
- Space Telescope Science Institute
- GTO-8041
- Space Telescope Science Institute
- GO-8157
- Space Telescope Science Institute
- Swedish National Space Board (SNSB)
- AR-9930
- Space Telescope Science Institute
- S-56500-D
- NASA
- Created
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2011-06-02Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field