The high-field polar RX J1007.5–2017

¹ MPI für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching, Germany
² Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
e-mail: k.beuermann@t-online.de
³ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
⁴ MPI für extraterrestrische Physik, Giessenbachstr. 6, 85740 Garching, Germany

Received: 23 June 2012
Accepted: 31 August 2012

Abstract

We report optical and X-ray observations of the high-field polar RX J1007.5–2017 performed between 1990 and 2012. It has an orbital period of 208.60 min determined from the ellipsoidal modulation of the secondary star in an extended low state. The spectral flux of the dM3 – secondary star yields a distance of 790  ±  105 pc. At low accretion levels, RX J1007.5–2017 exhibits pronounced cyclotron emission lines. The second and third harmonic fall in the optical regime and yield a field strength in the accretion spot of 94 MG. The source is highly variable on a year-to-year basis and was encountered at visual magnitudes between V ~ 20 and V ~ 16. In the intermediate state of 1992 and 2000, the soft X-ray luminosity exceeds the sum of the luminosities of the cyclotron source, the hard X-ray source, and the accretion stream by an order of magnitude. An X-ray high state, corresponding to the brightest optical level, has apparently not been observed so far.