2006/02/17 by Gregory J. Herczeg, Jeffrey L. Linsky, Frederick M. Walter +5 · 99 citations
Chemistry · Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Emission spectrum #Fluorescence #Molecular Spectroscopy and Structure #Optics #Physics #Spectral line #Stars #Stellar, planetary, and galactic studies #T Tauri star #astro-ph
paper · pdf · doi:10.1086/503558
published in The Astrophysical Journal Supplement Series 165(1), 256-282 (Institute of Physics) · 38 pages, 18 figures, 14 tables. Accepted by ApJS
arxiv created 2006/02/17 · openalex publication_date 2006/07/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
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.