Astronomy and Astrophysics – Astrophysics
Scientific paper
Feb 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993a%26a...268..192g&link_type=abstract
Astronomy and Astrophysics (ISSN 0004-6361), vol. 268, no. 1, p. 192-200.
Astronomy and Astrophysics
Astrophysics
45
Stellar Magnetic Fields, Stellar Mass Accretion, Stellar Spectra, Variable Stars, Astronomical Spectroscopy, Line Spectra, Photosphere, Stellar Models
Scientific paper
We present a series of CCD spectra of the very active T Tauri star DR Tau. The amount of veiling of the stellar absorption lines was unusually large and highly variable on timescales as short as a few hours. Inverse P Cygni profiles are visible over a wide range of line excitation: Na I D, Fe II, H-beta, and even He I A5867. The equivalent widths of the emission and the inverse P Cygni absorption lines are 2 to 10 times larger in the high veiling state. However, the velocity structure of the inverse P Cygni lines is not affected by changes in the amount of veiling. We find a factor of 2-3 difference in the mean temperatures of the veiling continuum source between the most extreme veiling states. If the continuum source is an optically thick spot on the star itself, the projected area was 60 percent of the star in the 'low' and less than about 30 percent in the 'high' veiling states, respectively. These observations are most easily explained by magnetic accretion models, where an accretion shock is formed by matter falling freely along field lines from the circumstellar disk onto the star.
Guenther Eike E.
Hessman Frederic V.
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