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Astron. Astrophys. 355, 1031-1040 (2000)

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Rapidly oscillating Ap stars versus non-oscillating Ap stars

S. Hubrig 1, N. Kharchenko 2, G. Mathys 3 and P. North 4

1 Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
2 Main Astronomical Observatory, Golosiiv, Kiev-127, 03680 Ukraine
3 European Southern Observatory, Casilla 19001, Santiago 19, Chile
4 Institut d'Astronomie de l'Universite de Lausanne, 1290 Chavannes-des-bois, Switzerland

Received 12 October 1999 / Accepted 21 January 2000


The positions in the HR diagram and the kinematic characteristics of rapidly oscillating and non-oscillating chemically peculiar stars are obtained using new Hipparcos proper motions and parallaxes, and our own radial velocity measurements. We find that rapidly oscillating stars, as a group, are ([FORMULA]) mag above the zero-age main sequence (ZAMS), while the non-oscillating stars are ([FORMULA]) mag above the ZAMS and so appear slightly more evolved on average. From the comparison of the kinematical characteristics, we conclude that both groups are very similar. The results of radial velocity measurements indicate that there is a real deficiency of binaries among rapidly oscillating stars. Presently, no such star is known to be a spectroscopic binary.

Key words: stars: binaries: general – stars: chemically peculiar – stars: kinematics – stars: oscillations

Send offprint requests to: S. Hubrig (Shubrig@astro.physik.uni-potsdam.de)

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© European Southern Observatory (ESO) 2000

Online publication: March 21, 2000