EDP Sciences
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Volume 393, Number 2, October II 2002
Page(s) 563 - 571
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20021085

A&A 393, 563-571 (2002)
DOI: 10.1051/0004-6361:20021085

Velocity variability of semiregular and irregular variables

T. Lebzelter1 and K. H. Hinkle2

1  Institut für Astronomie, Universität Wien, Türkenschanzstr. 17, 1180 Vienna, Austria
2  National Optical Astronomy Observatory (Operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with the National Science Foundation.) , 950 N. Cherry Avenue, PO Box 26732, Tucson, Arizona 85726, USA

(Received 17 April 2002 / Accepted 11 July 2002 )

We compare velocities from near infrared lines with center-of-mass velocities for a sample of semiregular and irregular variables to search for indications for a convective blueshift. It is shown that a general blueshift is present but that the light variability is obviously not dominated by convective cells but rather by stellar pulsation. All stars of our sample show a similar shape and amplitude in the velocity variations. Long secondary periods are a common feature in these objects and strongly influence the measured velocity shifts. The star V366 Aql is found to be the first SRV showing line doubling.

Key words: stars: variables: general -- stars: late-type -- stars: AGB and post-AGB -- stars: atmospheres

Offprint request: T. Lebzelter, lebzelter@astro.univie.ac.at

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