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RX J1313.2-3259, a long-period Polar discovered with ROSAT *
H.-C. Thomas 1,
K. Beuermann 2,3,
V. Burwitz 3,2,
K. Reinsch 2 and
A.D. Schwope 4
Received 7 September 1999 / Accepted 5 November 1999
We report observations of a new AM Herculis binary identified as the optical counterpart of the X-ray source RX J1313.2-3259, detected during the ROSAT All-Sky Survey (RASS). It has an orbital period of 251 min and is strongly modulated at optical wavelengths. The long-term behavior is characterized by a pronounced variation in X-rays between the RASS and two subsequent pointings (decrease by a factor 40 in count rate) and by moderate changes in the optical brightness (up to a factor 5). The X-ray spectrum is dominated by a soft quasi-blackbody component, with a smaller contribution from thermal bremsstrahlung. Measurements of high circular polarization confirm its classification as a Polar with a magnetic field strength of 56 MG. The average visual magnitude of RX J1313.2-3259 is , for its distance we get 200 pc.
Key words: stars: novae, cataclysmic variables stars: magnetic fields stars: individual: RX J1313.2 3259 stars: binaries: close X-rays: stars accretion, accretion disks
* Based in part on observations collected at the European Southern Observatory, La Silla, Chile with the ESO/MPI 2.2m telescope in MPI time and with various telescopes in ESO time (ESO Nos. 50.6-017, 50.6-021, 54.D-0698, 55.D-0383, 56.D-0552, 56.D-0561, 61.D-0415).
Send offprint requests to: H.-C. Thomas (email@example.com)
Online publication: December 17, 1999