Carina OB Stars: X-ray Signatures of Wind Shocks and Magnetic Fields

Marc Gagne1, Garrett Fehon1, Michael R. Savoy1, David H. Cohen2, Leisa K. Townsley3, Patrick S. Broos3, Matthew S. Povich3, Michael F. Corcoran4, Nolan R. Walborn5, Nancy Remage Evans6, Anthony F.J. Moffat7, Yael Naze8 and Lidia M. Oskinova9

1 - Department of Geology and Astronomy, West Chester University, West Chester, PA 19383
2 - Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA 19081
3 - Department of Astronomy & Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802
4 - CRESST and X-ray Astrophysics Laboratory, NASA/GSFC, Greenbelt, MD 20771
5 - Space Telescope Science Institute, Baltimore, MD 21218
6 - Smithsonian Astrophysical Observatory, MS 4, 60 Garden St., Cambridge, MA 02138
7 - Departement de Physique, Universite de Montreal, Succursale Centre-Ville, Montr'eal, QC, H3C 3J7, Canada
8 - GAPHE, D'epartement AGO, Universit'e de Li`ege, Allee du 6 Aout 17, Bat. B5C, B4000-Liege, Belgium and Research Associate FRS-FNRS
9 - Institute for Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany

The Chandra Carina Complex contains 200 known O- and B type stars. The Chandra survey detected 68 of the 70 O stars and 61 of 127 known B0-B3 stars. We have assembled a publicly available optical/X-ray database to identify OB stars that depart from the canonical Lx/Lbol relation, or whose average X-ray temperatures exceed 1 keV. Among the single O stars with high kT we identify two candidate magnetically confined wind shock sources: Tr16-22, O8.5 V, and LS 1865, O8.5 V((f)). The O4 III(fc) star HD 93250 exhibits strong, hard, variable X-rays, suggesting it may be a massive binary with a period of >30 days. The visual O2 If* binary HD 93129A shows soft 0.6 keV and hard 1.9 keV emission components, suggesting embedded wind shocks close to the O2 If* Aa primary, and colliding wind shocks between Aa and Ab. Of the 11 known O-type spectroscopic binaries, the long orbital-period systems HD 93343, HD 93403 and QZ Car have higher shock temperatures than short-period systems such as HD 93205 and FO 15. Although the X-rays from most B stars may be produced in the coronae of unseen, low-mass pre-main-sequence companions, a dozen B stars with high Lx cannot be explained by a distribution of unseen companions. One of these, SS73 24 in the Treasure Chest cluster, is a new candidate Herbig Be star.

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