Journal Article

The same, but different: stochasticity in binary destruction

Richard J. Parker and Simon P. Goodwin

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 424, issue 1, pages 272-281
Published in print July 2012 | ISSN: 0035-8711
Published online July 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21190.x
The same, but different: stochasticity in binary destruction

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Observations of binaries in clusters tend to be of visual binaries with separations of tens to hundreds of au. Such binaries are ‘intermediates’ and their destruction or survival depends on the exact details of their individual dynamical history. We investigate the stochasticity of the destruction of such binaries and the differences between the initial and processed populations using N-body simulations. We concentrate on Orion nebula cluster-like clusters, where the observed binary separation distribution ranges from 62 to 620 au.

We find that, starting from the same initial binary population in statistically identical clusters, the number of intermediate binaries that are destroyed after 1 Myr can vary by a factor of >2, and that the resulting separation distributions can be statistically completely different in initially substructured clusters. We also find that the mass ratio distributions are altered (destroying more low mass-ratio systems), but not as significantly as the binary fractions or separation distributions. We conclude that finding very different intermediate (visual) binary populations in different clusters does not provide conclusive evidence that the initial populations were different.

Keywords: methods: numerical; binaries: general; stars: formation; open clusters and associations: general

Journal Article.  6299 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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