EDP Sciences
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Volume 403, Number 1, May III 2003
Page(s) 239 - 246
Section Formation and evolution of planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20030248

A&A 403, 239-246 (2003)
DOI: 10.1051/0004-6361:20030248

Long term disc variability in the Be star o Andromedae

J. S. Clark1, A. E. Tarasov2 and E. A. Panko3

1  Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, England, UK
2  Crimean Astrophysical Observatory and Isaac Newton Institute of Chile, Crimean Branch, Naucny, Crimea, 98409, Ukraine
3  Kalinenkov Astronomical Observatory, Nikolaev State University, Nikolskaya, 24, Nikolaev, 54030, Ukraine

(Received 11 December 2002 / Accepted 19 February 2003 )

We present 18 years of high resolution and S/N H $\alpha$ spectroscopy of the Be shell star o And , obtained between 1985-2002. Spectra taken during late 1985 show a pure photospheric profile, with disc re-formation commencing in 1986; a process that is found to occur over long timescales (~10 3 days). Analysis of the evolution of the properties of the H $\alpha$ shell profile suggest that the disc kinematics are dominated by rotational motion. It has been shown that disc loss in o And occurs "inside out"; we find that the disc also appears to be rebuilt in a similar manner, with disc material gradually diffusing to larger radii. The long timescale for changes in the bulk properties of the disc, domination of rotational over radial velocities and manner of disc loss and formation are all consistent with the predictions of the viscous decretion disc model for Be star discs.

Key words: stars: circumstellar matter -- stars: early type -- stars: individual: o Andromedae

Offprint request: J. S. Clark, jsc@star.ucl.ac.uk

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