2007/02/14 by A. K. Dupree, Dupree, A. K., E. H. Avrett +9
Physics and Astronomy · #Astro and Planetary Science #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #FOS: Physical sciences #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0702395
7 pages, 6 figures. To appear in the 'Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, (Cool Stars 14)', ASP Conf. Series
arxiv created 2007/02/14 · openalex publication_date 2007/02/14 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A continuous set of echelle spectra of TW Hya, taken with the MIKE spectrograph on the Magellan2/Clay telescope at Las Campanas Observatory in April 2006 reveals systematic variations in the flux, velocity, and profile of the H-alpha emission line which appear to be consistent with the photometric period of 2.8 days. Absorption features recur at high outflow velocities in the wind. This behavior suggests that: (a) accretion is not uniformly distributed over the stellar hemisphere in view; (b) stable structures are present in the chromosphere, most likely due to the stellar magnetic field configuration. Semi-empirical models of the atmosphere are constructed to reproduce line profiles of H-alpha and He I, 10830A and to define the wind structure. These preliminary calculations suggest the mass loss rate is variable and comparable to H-alpha mass accretion rates in the literature, requiring a very efficient mechanism if the wind is powered only by accretion.