paper

Spectroscopy of the enigmatic short-period cataclysmic variable IR Com in an extended low state

arXiv:1401.5055 · doi:10.1093/mnrasl/slu049

Abstract

We report the occurrence of a deep low state in the eclipsing short-period cataclysmic variable IR Com, lasting more than two years. Spectroscopy obtained in this state shows the system as a detached white dwarf plus low-mass companion, indicating that accretion has practically ceased. The spectral type of the companion derived from the SDSS spectrum is M6-7, somewhat later than expected for the orbital period of IR Com. Its radial velocity amplitude, K_2=419.6+-3.4 km/s, together with the inclination of 75-90deg implies 0.8Msun<Mwd<1.0Msun. We estimate the white dwarf temperature to be ~15000K, and the absence of Zeeman splitting in the Balmer lines rules out magnetic fields in excess of ~5 MG. IR Com still defies an unambiguous classification, in particular the occurrence of a deep, long low state is so far unique among short-period CVs that are not strongly magnetic.

Revised version, MNRAS Letters in press

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