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The Origins of Fluorescent H_2 Emission From T Tauri Stars

Herczeg, Gregory J. and Linsky, Jeffrey L. and Walter, Frederick M. and Gahm, Gösta F. and Johns-Krull, Christopher M. (2006) The Origins of Fluorescent H_2 Emission From T Tauri Stars. Astrophysical Journal Supplement Series, 165 (1). pp. 256-282. ISSN 0067-0049.

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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.

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Herczeg, Gregory J.0000-0002-7154-6065
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.
Funding AgencyGrant Number
Space Telescope Science InstituteGTO-7718
Space Telescope Science InstituteGTO-8041
Space Telescope Science InstituteGO-8157
Swedish National Space Board (SNSB)UNSPECIFIED
Space Telescope Science InstituteAR-9930
Subject Keywords:accretion, accretion disks; circumstellar matter; line: identification; stars: pre–main-sequence; ultraviolet: stars
Issue or Number:1
Record Number:CaltechAUTHORS:20110602-110356928
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Official Citation:The Origins of Fluorescent H2 Emission From T Tauri StarsGregory J. Herczeg et al. 2006 ApJS 165 256
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23876
Deposited By: Jason Perez
Deposited On:02 Jun 2011 20:14
Last Modified:03 Oct 2019 02:50

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