2003/01/07 by Jeffrey S. Bary, J. S. Bary, David A. Weintraub +3
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/367719
published as Astrophys.J. 586 (2003) 1136-1147 · 39 pages, 4 figures
arxiv created 2003/01/07 · openalex publication_date 2003/03/25 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We report the detection of quiescent H 2 emission in the v = 1 → 0 S (1) line at 2.12183 μm in the circumstellar environment of two classical T Tauri stars, GG Tau A and LkCa 15, in high-resolution ( R ≃ 60,000) spectra, bringing to four, including TW Hya and the weak-lined T Tauri star DoAr 21, the number of T Tauri stars showing such emission. The equivalent widths of the H 2 emission line lie in the range 0.02-0.10 Å, and in each case the central velocity of the emission line is centered at the star's systemic velocity. The line widths range from 9 to 14 km s -1 , in agreement with those expected from gas in Keplerian orbits in circumstellar disks surrounding K-type stars at distances ≥10 AU from the sources. UV fluorescence and X-ray heating are likely candidate mechanisms responsible for producing the observed emission. We present mass estimates from the measured line fluxes and show that the estimated masses are consistent with those expected from the possible mechanisms responsible for stimulating the observed emission. The high temperatures and low densities required for significant emission in the v = 1 → 0 S (1) line suggests that we have detected reservoirs of hot H 2 gas located in the low-density upper atmospheres of circumstellar disks of these stars.