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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 660754.0, MPI für Astronomie / Publikationen_mpia
Massive binaries in the Cepheus OB2/3 region. Constraining the formation mechanism of massive stars
Authors:Peter, D.; Feldt, M.; Henning, T.; Hormuth, F.
Date of Publication (YYYY-MM-DD):2012
Journal Abbrev.:Astronomy and Astrophysics
Start Page:id.A74
Audience:Not Specified
Abstract / Description:Context. Two different formation scenarios for stars of masses larger than 10 M&sun; exist. Although simulations within both scenarios are capable of producing stars up to the highest observed masses, the relevance of the two formation scenarios for massive star-formation is not yet clear. <BR /> Aims: We aim to detect companions to massive stars to constrain the binary parameters of the multiple systems. These findings will help to constrain the formation of massive stars. <BR /> Methods: We performed z'-band observations of massive and intermediate-mass stars in the Cep OB2/3 associations with the Lucky imaging camera AstraLux on the 2.2 m telescope of the Calar Alto observatory. The analysis aimed at detecting binary systems with separations out to 2".2 (~1700 AU), the inner limit depending on the contrast. The maximum contrast of 7 mag in z' (corresponding to a mass contrast of 17:1 versus an O9V primary) requires a minimum separation of 0".7 (~550 AU). <BR /> Results: We found 28 new companions for our sample of 148 intermediate-mass and massive stars in Cep OB2/3. The companion star fraction of the massive stars is 0.7; about 50% of the systems are triples. The mass function of the companions to the massive stars is strongly top-heavy. We found that the sample parameters closely agreed with those found in the Orion Trapezium cluster. <BR /> Conclusions: The multiplicity of massive stars seems to be significantly higher than that of intermediate-mass stars, independently of the environment. The comparison of our findings with the theories of massive star-formation favor the formation of massive stars by the fragmentation of proto-stellar cores combined with competitive accretion. Appendix A in available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A>
Free Keywords:binaries: close; stars: formation; stars: massive
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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