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Probing small scale structure in the atmosphere of V471 Tauri
Author(s) -
Walter F. M.
Publication year - 2004
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200310209
Subject(s) - physics , astrophysics , atmosphere (unit) , white dwarf , radius , photosphere , t tauri star , effective temperature , spectral line , astronomy , stellar atmosphere , star (game theory) , radial velocity , brightness , stars , computer security , computer science , thermodynamics
The white dwarf in the eclipsing binary system V471 Tau is viewed through the atmosphere of the active K star prior to ingress and after egress. In the far UV the surface brightness of the hot white dwarf far outshines the K star emission. We can use this to probe the structure of the extended K star atmosphere along one line of sight, in absorption, on spatial scales of the radius of the white dwarf (10,000 km). The time series of HST/STIS spectra which show a hot (>250,000 K) extended (>1 K star radius) atmosphere around the K star. We see discrete structures in the velocity‐resolved spectra, on spatial scales of less than 100,000 km. The mean velocity is that expected of gas in co‐rotation with the K star, but the discrete velocity structures have excursions of up to 70 km/s from the mean. The mean temperature seems to increase with height above the K star photosphere. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)