The Volume-limited A-Star (VAST) survey - II. Orbital motion monitoring of A-type star multiples

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DOIResolve DOI: http://doi.org/10.1111/j.1365-2966.2011.20397.x
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TypeArticle
Journal titleMonthly Notices of the Royal Astronomical Society
ISSN0035-8711
Volume422
Issue4
Pages27652785; # of pages: 21
AbstractAs a part of our ongoing Volume-limited A-Star (VAST) adaptive optics survey, we have obtained observations of 26 binary systems with projected separations <100 au, 13 of which have sufficient historical measurements to allow for refinement of their orbital elements. For each system with an estimated orbit, the dynamical system mass obtained was compared with the system mass estimated from mass-magnitude relations. Discrepancies between the dynamical and theoretical system mass can be explained by the presence of a previously unresolved spectroscopic component or by a non-solar metallicity of the system. Using this approach to infer the presence of additional companions, a lower limit to the fraction of binaries, triples and quadruples can be estimated as 39, 46 and 15per cent for systems with at least one companion within 100 au. The fraction of multiple systems with three or more components shows a relative increase compared to the fraction for solar-type primaries resolved in previous volume-limited surveys. The observations have also revealed a pair of potentially young (<100Myr) M dwarf companions, which would make an ideal benchmark for the theoretical models during the pre-main-sequence contraction phase for M dwarfs. In addition to those systems with orbit fits, we report 13 systems for which further orbital monitoring observations are required, 11 of which are newly resolved as a part of the VAST survey.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); National Science Infrastructure
Peer reviewedYes
NPARC number21270257
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Record identifier8a883d51-02fa-46c4-9581-802a675808cb
Record created2014-01-16
Record modified2016-05-09
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