The search for low-mass companions of B stars in the Carina Nebula Cluster Trumpler 16

Evans, Nancy Remage and DeGioia-Eastwood, Kathleen and Gagne, Marc and Townsley, Leisa and Broos, Patrick and Wolk, Scott and Naze, Yael and Corcoran, Michael and Oskinova, Lida and Moffat, Anthony F. J. and Wang, Junfeng and Walborn, Nolan R. (2011) The search for low-mass companions of B stars in the Carina Nebula Cluster Trumpler 16. Astrophysical Journal Supplement Series, 194 (1). ISSN 1538-4365

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Abstract

We have developed lists of likely B3-A0 stars (called "late B" stars) in the young cluster Trumpler 16. The following criteria were used: location within 3' of η Car, an appropriate V and B - V combination, and proper motion (where available). Color and magnitude cuts have been made assuming an E(B - V) = 0.55 mag +/- 0.1, which is a good approximation close to the center of Trumpler 16. These lists have been cross-correlated with X-ray sources found in the Chandra Carina Complex Project. Previous studies have shown that only very rarely (if at all) do late main-sequence B stars produce X-rays. We present evidence that the X-ray-detected sources are binaries with low-mass companions, since stars less massive than 1.4 M☉ are strong X-ray sources at the age of the cluster. Both the median X-ray energies and X-ray luminosities of these sources are in good agreement with values for typical low-mass coronal X-ray sources. We find that 39% of the late B stars based on a list with proper motions have low-mass companions. Similarly, 32% of a sample without proper motions have low-mass companions. We discuss the X-ray detection completeness. These results on low-mass companions of intermediate-mass stars are complementary to spectroscopic and interferometric results and probe new parameter space of low-mass companions at all separations. They do not support a steeply rising distribution of mass ratios to low masses for intermediate-mass (5 M☉) primaries, such as would be found by random pairing from the initial mass function.

Item Type:	Article
ID number or DOI:	10.1088/0067-0049/194/1/13
Keywords:	catalog; chandra; chemically peculiar stars; complex project; eta-carinae; open clusters and associations: individual (Trumpler 16); radio; stars: massive; x-ray-emission
Subjects:	Q Science > QB Astronomy
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > Physics and Astronomy
Date Deposited:	24 Aug 2015 19:59
URI:	http://openknowledge.nau.edu/id/eprint/110

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