A Multiplicity Census of Intermediate-mass Stars in Scorpius-Centaurus
Abstract
Stellar multiplicity properties have been studied for the lowest and the highest stellar masses, but intermediate-mass stars from F-type to late A-type have received relatively little attention. Here, we report on a Gemini/NICI snapshot imaging survey of 138 such stars in the young Scorpius-Centaurus (Sco-Cen) region, for the purpose of studying multiplicity with sensitivity down to planetary masses at wide separations. In addition to two brown dwarfs and a companion straddling the hydrogen-burning limit which we reported previously, here we present 26 new stellar companions and determine a multiplicity fraction within 0.''1-5.''0 of 21% ± 4%. Depending on the adopted semimajor axis distribution, our results imply a total multiplicity in the range of ~60%-80%, which further supports the known trend of a smooth continuous increase in the multiplicity fraction as a function of primary stellar mass. A surprising feature in the sample is a distinct lack of nearly equal-mass binaries, for which we discuss possible reasons. The survey yielded no additional companions below or near the deuterium-burning limit, implying that their frequency at >200 AU separations is not quite as high as might be inferred from previous detections of such objects within the Sco-Cen region.
Based on Gemini observations from programs GS-2011A-Q-44, GS-2012A-Q-18, GS-2012A-DD-6, GS-2013A-Q-21, and on ESO observations from program 089.C-0422(A).- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2013
- DOI:
- 10.1088/0004-637X/773/2/170
- arXiv:
- arXiv:1307.2243
- Bibcode:
- 2013ApJ...773..170J
- Keywords:
-
- binaries: general;
- brown dwarfs;
- planetary systems;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 23 pages, 5 figures, accepted for publication in ApJ