Modeling of Oxygen-Neon Dominated Accretion Disks in Ultracompact X-ray Binaries: 4U1626-67

Abstract

We report on first results of computing synthetic spectra from H/He-poor accretion disks in ultracompact LMXBs. We aim at the determination of the chemical composition of the very low-mass donor star, which is the core of a former C/O white dwarf. The abundance analysis allows to draw conclusions on gravitational settling in WDs which is an important process affecting cooling times and pulsational g-mode periods.

to be published in: Compact Binaries in the Galaxy and Beyond (IAU Coll. 194) 3 pages, 1 figure