Radial velocities of massive stars in Cyg OB2 Virtual Observatory Resource

Authors
  1. Kiminki D.C.
  2. Kobulnicky H.A.
  3. Published by
    CDS
Abstract

This work provides a statistical analysis of the massive star binary characteristics in the Cygnus OB2 association using radial velocity information of 114 B3-O5 primary stars and orbital properties for the 24 known binaries. We compare these data to a series of Monte Carlo simulations to infer the intrinsic binary fraction and distributions of mass ratios, periods, and eccentricities. We model the distribution of mass ratio, log-period, and eccentricity as power laws and find best-fitting indices of {alpha}=0.1+/-0.5, {beta}=0.2+/-0.4, and {gamma}=-0.6+/-0.3, respectively. These distributions indicate a preference for massive companions, short periods, and low eccentricities. Our analysis indicates that the binary fraction of the cluster is 44%+/-8% if all binary systems are (artificially) assumed to have P<1000 days; if the power-law period distribution is extrapolated to 10^4^ years, then a plausible upper limit for bound systems, the binary fraction is ~90%+/-10%. Of these binary (or higher order) systems, ~45% will have companions close enough to interact during pre- or post-main-sequence evolution (semi-major axis <~4.7AU). The period distribution for P<26 days is not well reproduced by any single power law owing to an excess of systems with periods around 3-5 days (0.08-0.31AU) and a relative shortage of systems with periods around 7-14 days (0.14-0.62AU). We explore the idea that these longer-period systems evolved to produce the observed excess of short-period systems. The best-fitting binary parameters imply that secondaries generate, on average, ~16% of the V-band light in young massive populations. This means that photometrically based distance measurements for young massive clusters and associations will be systematically low by ~8% (0.16 mag in the distance modulus) if the luminous contributions of unresolved secondaries are not taken into account.

Keywords
  1. early-type-stars
  2. radial-velocity
  3. stellar-associations
  4. spectroscopic-binary-stars
Bibliographic source Bibcode
2012ApJ...751....4K
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/751/4
IVOA Identifier IVOID
ivo://CDS.VizieR/J/ApJ/751/4
Document Object Identifer DOI
doi:10.26093/cds/vizier.17510004

Access

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https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/751/4
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/751/4
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/751/4
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https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/751/4/stars?
https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/751/4/stars?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/751/4/stars?

History

2014-01-29T08:43:31Z
Resource record created
2014-01-29T08:43:31Z
Created
2017-12-18T07:56:49Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr