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Astron. Astrophys. 319, 481-486 (1997)


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Red giants in open clusters

VI. Orbits of ten spectroscopic binaries * **

J.-C. Mermilliod 1, J. Andersen 2 and M. Mayor 3

1 Institut d'Astronomie de l'Université de Lausanne, CH-1290 Chavannes-des-Bois, Switzerland
2 Niels Bohr Institute for Astronomy, Physics, and Geophysics, Astronomical Observatory, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
3 Observatoire de Genève, CH-1290 Sauverny, Switzerland

Received 11 July 1996 / Accepted 23 July 1996

Abstract

We present new orbits for ten (single-lined) spectroscopic binaries in seven open clusters: NGC 2489, 2567, 3033, 5822, 6134, 6664 and IC 2488 based on 243 individual radial velocities obtained with the southern CORAVEL scanner. The orbital periods range from 98.5 to 3566 days. The shortest-period orbit is circular, as expected. Seven of the binaries are confirmed cluster members, one is a possible member, and two are clearly non-members. Maximum masses from photometric separation and minimum masses from the spectroscopic orbits define the mass of the secondaries within an interval of [FORMULA] - [FORMULA] = 0.5 [FORMULA]. NGC 6664 #54 seems to have a rather massive secondary (M [FORMULA] 3 [FORMULA]), but the UBV colours appear normal for a luminous red giant, while significantly bluer [FORMULA] and [FORMULA] colours would be expected. It could be a triple system, the secondary being itself a short period binary. This paper brings the number of orbits published in this programme to 53, 45 of which are confirmed red-giant cluster members and 8 are non-members.

Key words: cluster: open – binaries: spectroscopic – stars: fundamental parameters

* Based on observations collected with the Danish 1.54-m telescope at the European Southern Observatory, La Silla, Chile
** Table 3 is only available in electronic form at the CDS via anonymous ftp to cds.u-strasbg.f (130.79.128.5) or via http://cdsweb.u-strasbg.fr/abstract.html

Send offprint requests to: J.-C. Mermilliod

© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998

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