Get access

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

Authors

  • R. J. De Rosa,

    Corresponding author
    1. College of Engineering, Mathematics and Physical Sciences, University of Exeter, Physics Building, Stocker Road, Exeter EX4 4QL
      E-mail: derosa@astro.ex.ac.uk Based on observations obtained at the Canada–France–Hawaii Telescope (CFHT) under programme IDs 2001AF11, 2008AC22, 2009BC06, 2010AC14 and 2011AC11. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programme IDs 272.D-5068(A), 074.D-0180(A), 076.C-0270(A), 076.D-0108(A), 077.D-0147(A) and 080.D-0348(A). Based on observations obtained at the Gemini Observatory under programme IDs GN2008A-Q-74, GN-2008B-Q-119 and GN-2010A-Q-75.
    Search for more papers by this author
  • J. Patience,

    1. College of Engineering, Mathematics and Physical Sciences, University of Exeter, Physics Building, Stocker Road, Exeter EX4 4QL
    Search for more papers by this author
  • A. Vigan,

    1. College of Engineering, Mathematics and Physical Sciences, University of Exeter, Physics Building, Stocker Road, Exeter EX4 4QL
    Search for more papers by this author
  • P. A. Wilson,

    1. College of Engineering, Mathematics and Physical Sciences, University of Exeter, Physics Building, Stocker Road, Exeter EX4 4QL
    Search for more papers by this author
  • A. Schneider,

    1. Physics and Astronomy, University of Georgia, 240 Physics, Athens, GA 30602, USA
    Search for more papers by this author
  • N. J. McConnell,

    1. Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720, USA
    Search for more papers by this author
  • S. J. Wiktorowicz,

    1. Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720, USA
    2. Department of Astronomy, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
    Search for more papers by this author
  • C. Marois,

    1. NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
    Search for more papers by this author
  • I. Song,

    1. Physics and Astronomy, University of Georgia, 240 Physics, Athens, GA 30602, USA
    Search for more papers by this author
  • B. Macintosh,

    1. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
    Search for more papers by this author
  • J. R. Graham,

    1. Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720, USA
    2. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, ON M55 3H8, Canada
    Search for more papers by this author
  • M. S. Bessell,

    1. Mount Stromlo and Siding Spring Observatories, Institute of Advanced Studies, The Australian National University, Weston Creek P.O., ACT 2611, Australia
    Search for more papers by this author
  • R. Doyon,

    1. Dépt de Physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7, Canada
    Search for more papers by this author
  • O. Lai

    1. Canda–France–Hawaii Telescope, 65-1238 Mamalahoa Highway, Kamuela, HI 96745, USA
    Search for more papers by this author

E-mail: derosa@astro.ex.ac.uk

Based on observations obtained at the Canada–France–Hawaii Telescope (CFHT) under programme IDs 2001AF11, 2008AC22, 2009BC06, 2010AC14 and 2011AC11. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programme IDs 272.D-5068(A), 074.D-0180(A), 076.C-0270(A), 076.D-0108(A), 077.D-0147(A) and 080.D-0348(A). Based on observations obtained at the Gemini Observatory under programme IDs GN2008A-Q-74, GN-2008B-Q-119 and GN-2010A-Q-75.

ABSTRACT

As 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 15 per 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 (<100 Myr) 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.

Get access to the full text of this article

Ancillary