arXiv subjects

V. Burwitz

Publications and source records attributed to V. Burwitz.

92 records · Page 6Linked to original sources

arXiv1999

RX J1313.2-3259, a long-period Polar discovered with ROSAT

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 V = 16 mag, for its distance we get 200 pc.

astro-ph↗

arXiv1999

Optical observations of the black hole candidate XTE J1550-564 during the Sep/Oct 1998 outburst

We report here optical observations during the September/October 1998 outburst of the black hole candidate XTE J1550-564. CCD photometry was obtained for the optical counterpart with the 0.9m Dutch telescope at La Silla since the onset of this event. We analysed 211 U, V and i frames, from Sep 10 to Oct 23. Stochastic flaring activity was observed on Sep 11-16, but no evidence for a superhump period, as seen in other soft X-ray transients, was found. An optical flare nearly simultaneous to an X-ray flare that occurred on Sep 21 was observed in the V-band. A reddened optical spectrum showed the typical emission lines corresponding to X-ray transients in outburst. From the interstellar absorption lines, we derive E(B-V) = 0.70 +/- 0.10 and suggest a distance of about 2.5 kpc. In such case, M_{B} = +7 mag. for the progenitor, which is consistent with the spectral type of a low-mass K0-K5 main-sequence companion.

astro-ph↗