Strong flickerings in a black hole X-ray transient V616 Mon.

ATel #7547; S. Shugarov (Astronomical Institute, Slovak Academy of Sciences, Tatranska Lomnica and Sternberg Astronomical Institute, Lomonosov Moscow State Univesity), N. Katysheva and N. Gladilina (Sternberg Astronomical Institute, Lomonosov Moscow State Univesity)
on 21 May 2015; 20:13 UT
Credential Certification: Sergey Shugarov (s.shugarov@gmail.com)

Tweet

V616 Mon = A0620–00 is a prototype of close binaries known as black hole X–ray transients with a black hole primary and low mass secondary (Harrison et al., 2007, AJ, 133, 162). It was discovered by the Ariel-5 satellite on August 3, 1975 (Elvis et al., 1975, Nature, 257, 656) as a bright X–ray nova. The nova reached 11.4^m in B. After dramatic fading brightness in the April 1976 (Martynov et al., 1976, IAUCirc. No 2953), V616 Mon passed into a quiescent state (Lyuty, Shugarov, 1978, Soviet Astron. Let., 5, 102.).
The previous outburst of this object in November 1917 was found on the archive plates of the Harvard College Observatory when it brightness reached pg=12^m (Eachus et al., 1976, ApJ, 203, 17) and on two Simeiz plates taken on January 20, 1918 (JD 2421461.2), pg = 12.4^m, (Shugarov, 1976, Perem. Zvezdy, 20, 251).
Red and infrared photometry by Leibowitz et al. (1998, MNRAS, 300, 463), Celino et al. (2001, AJ, 122, 2668) and Harrison et al. (2007, AJ, 133, 162) showed an existence of the double humped light curve with a period of P=0.3230160^d and without any significant short-time variability.

We obtained time-resolved CCD photometry of V616 Mon (basically, in R or Rc-bands) during the last ten years using 60–125 cm telescopes of the Southern station of the Sternberg Astronomical Institute and the Astronomical Institute of the Slovak Academy of Sciences.
Our observations revealed some signs of flickerings during few nights in 2003 as well as strong flickerings that started in 2009. The analysis of our 2003–14 time series showed the superposition of the orbital (with a period 0.3230141^d) and rapid (with a characteristic time of about 30 min and an amplitude of 0.2^m–0.4^m) variability (see Fig.).

We think that this short-time variability is caused by the appearance of non-stationary processes in binary system possibly related to the increased mass of the accretion disk. Since the last outburst occurred 40 years ago, it is possible to expect the next outburst soon.

Our work was supported by grant of the Slovak Academy of Sciences VEGA No. 2/0002/13, RFBR grant 14–02–00825 and grant NSh–1675.20014.2.