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Astron. Astrophys. 330, 243-252 (1998)

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On the spectacular variations of Be stars

Evidence for a temporarily tilted circumstellar disk

W. Hummel

Universitätssternwarte München, Scheinerstr. 1, D-81679 München, Germany

Received 27 January 1997 / Accepted 15 September 1997


A new explanation for the spectacular emission line variations occuring in the Be stars [FORMULA]  Cas and 59 Cyg is presented. We propose a circumstellar Keplerian disk, tilted with respect to the equatorial plane. The precessing nodal and apsidal line causes a variation in the emission line widths and profile shapes. In particular the sequence of alternating shell-phases and narrow single-peak phases is proposed to be due to an apparent variation in the disk inclination.

Key words: line: formation; line: profiles; stars: circumstellar matter; stars: emission-line, Be; stars: individual: fl Cas ; stars: individual: 59 Cyg

© European Southern Observatory (ESO) 1998

Online publication: January 8, 1998