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Spectroscopic Binaries in Young Open Clusters

Published online by Cambridge University Press:  13 May 2016

Jean-Claude Mermilliod  and
Beatriz García
Jean-Claude Mermilliod
Affiliation:
Institut d'Astronomie, Université de Lausanne, CH-1290 Chavannes-des-Bois, Switzerland
Beatriz García
Affiliation:
CRICyT - Centro Regional de Investicaciones Científicas y Técnicas, CC 131–5500 Mendoza, Argentina

Abstract

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We have analysed the binarity and multiplicity characteristics of 120 O-type stars in 22 very young open clusters and found marked differences between the “rich” (N ≥ 6 O-type stars and primaries) and “poor” (N = 1) clusters. In the rich clusters, the binary frequencies vary between 14% (1 SB among 7 stars) and 80% (8 SBs among 10 stars). Multiple systems seem not to be frequent and stars are spread all over the cluster area. In poor clusters, the binary frequency of the O-type objects is nearly 100%, with orbital periods around 3 days. Several binaries are also eclipsing. Additional companions are always present. They form either hierarchical multiple stars or trapezium systems. These massive multiple systems are generally found close to the cluster center, although there are exceptions.

Type
VI. Binary Populations in Young Clusters
Information
Symposium - International Astronomical Union , Volume 200: The Formation of Binary Stars , 2001 , pp. 191 - 198
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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