Supersoft X-Ray Source CAL 83: A Possible AE Aqr-like System

A. Odendaal, P. J. Meintjes, P. A. Charles, A. F. Rajoelimanana
2015 Acta Polytechnica CTU Proceedings  
CAL 83 is a close binary supersoft X-ray source in the Large Magellanic Cloud. A ∼67 s periodicity detected in supersoft X-rays is most probably associated with the spin period of a highly spun-up white dwarf (WD). The variability in the period is ascribed to the obscuration of the WD by the hydrogen burning envelope surrounding it, rotating with a period that is close to, but not quite synchronized with, the WD rotation period. Optical spectra obtained with SALT exhibit accretion disc emission
more » ... etion disc emission lines with broad wing structures and P Cyg profiles, indicating mass outflows. Timing analysis of photometrical observations performed at the South African Astronomical Observatory (SAAO) revealed variable signals at ≤1 mHz which are thought to be associated with quasi-periodic oscillations from an accretion disc. The short spin period inferred for CAL 83 can be the result of spin-up by accretion disc torques during a long mass transfer history, placing this source on a similar evolutionary track as the cataclysmic variable AE Aqr.
doi:10.14311/app.2015.02.0094 fatcat:zxshre437rdd7ebncuz525vkoa