Carina OB stars: X-ray signatures of wind shocks and magnetic fields

Marc Gagné, Garrett Fehon, Michael R. Savoy, David H. Cohen, Leisa K. Townsley, Patrick S. Broos, Matthew S. Povich, Michael F. Corcoran, Nolan R. Walborn, Nancy Remage Evans, Anthony F.J. Moffat, Yal Nazé, Lida M. Oskinova

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Abstract

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 L X/L bol relation or whose average X-ray temperatures exceed 1keV. 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 that it may be a massive binary with a period of >30days. The visual O2 If* binary HD 93129A shows soft 0.6keV and hard 1.9keV 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 L X 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.

Original languageEnglish (US)
Article number5
JournalAstrophysical Journal, Supplement Series
Volume194
Issue number1
DOIs
StatePublished - May 2011

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Gagné, M., Fehon, G., Savoy, M. R., Cohen, D. H., Townsley, L. K., Broos, P. S., Povich, M. S., Corcoran, M. F., Walborn, N. R., Evans, N. R., Moffat, A. F. J., Nazé, Y., & Oskinova, L. M. (2011). Carina OB stars: X-ray signatures of wind shocks and magnetic fields. Astrophysical Journal, Supplement Series, 194(1), [5]. https://doi.org/10.1088/0067-0049/194/1/5