High-Resolution Spectroscopy of Ultracompact Binaries
Abstract
Observational evidence suggests that >10% of all known low-mass X-ray binaries have orbital periods shorter than 1 hour. These so-called ultracompact binaries require hydrogen-deficient or degenerate companions, usually assumed to be He white dwarfs. However, the Chandra spectrum of the ultracompact binary 4U 1626-67 revealed O and Ne emission and absorption features which led the authors to conclude that the donor is a carbon-oxygen WD. Unusual implied abundances from neutral absorption edges have also been found in 4 candidate ultracompact systems. I will present an overview of the Chandra and XMM-Newton spectral results from the known and candidate ultracompact binaries. In addition, I will address the implications of recent results on the nature of the companions in these systems and the formation of ultracompact binaries.
- Publication:
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X-ray Binaries in the Chandra and XMM-Newton Era (with an emphasis on Targets of Opportunity)
- Pub Date:
- November 2002
- Bibcode:
- 2002xrb..confE..17J
- Keywords:
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- Actively Accreting and Transient Binaries