The Multiplicity of Massive Stars: A High Angular Resolution Survey with the HST Fine Guidance Sensor

• Main Authors: Aldoretta, E. J, Caballero-Nieves, S. M, Gies, D. R, Nelan, E. P, Wallace, D. J, Hartkopf, W. I, Henry, T. J, Jao, W. -C, Apellániz, J. Maíz, Mason, B. D, Moffat, A. F. J, Norris, R. P, Richardson, N. D, Williams, S. J
• Format: Journal Article
• Language: English
• Published: 30-09-2014
• Subjects: Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.1410.0021

We present the results of an all-sky survey made with the Fine Guidance
Sensor on Hubble Space Telescope to search for angularly resolved binary
systems among the massive stars. The sample of 224 stars is comprised mainly of
Galactic O- and B-type stars and Luminous Blue Variables, plus a few luminous
stars in the Large Magellanic Cloud. The FGS TRANS mode observations are
sensitive to detection of companions with an angular separation between 0."01
and 1."0 and brighter than $\triangle m = 5$. The FGS observations resolved 52
binary and 6 triple star systems and detected partially resolved binaries in 7
additional targets (43 of these are new detections). These numbers yield a
companion detection frequency of 29% for the FGS survey. We also gathered
literature results on the numbers of close spectroscopic binaries and wider
astrometric binaries among the sample, and we present estimates of the
frequency of multiple systems and the companion frequency for subsets of stars
residing in clusters and associations, field stars, and runaway stars. These
results confirm the high multiplicity fraction, especially among massive stars
in clusters and associations. We show that the period distribution is
approximately flat in increments of log P. We identify a number of systems of
potential interest for long term orbital determinations, and we note the
importance of some of these companions for the interpretation of the radial
velocities and light curves of close binaries that have third companions.