CCD Photometry of the X-ray Nova V404 Cygni after the 1989 Outburst
Abstract
CCD photometry of the X-ray nova V404 Cyg, carried out 2.5, 6.5, 12.5, and 13 months after the May 1989 eruption, is presented. Despite a rather limited coverage, the data show evidence of the presence of a periodic modulation. The preliminary period is equal to 3.05 or 3.52 hours. Alternately, if V404 Cyg has a double-peaked light curve like other X-ray transients, the period is twice this value, about 6 hours. The amplitude of the light variations increased with fading brightness of the nova and was about 0.5 m in June 1990. It has been found that V404 Cyg has a close optical companion separated by 1.4 arcsec which is brighter than the nova at minimum. Based on the measurements and preoutburst photometry, it is estimated that the secondary component of the V404 Cyg system is a main-sequence F0-K2 star or a slightly evolved star if the spectral type is later than K2. This may explain why the nova differs during the outburst from other X-ray novae where the secondaries are usually late-K-type main-sequence stars.
- Publication:
-
Publications of the Astronomical Society of the Pacific
- Pub Date:
- February 1991
- DOI:
- 10.1086/132808
- Bibcode:
- 1991PASP..103..198U
- Keywords:
-
- Astronomical Photometry;
- Charge Coupled Devices;
- Main Sequence Stars;
- Novae;
- X Ray Stars;
- Companion Stars;
- F Stars;
- K Stars;
- Stellar Luminosity;
- Astrophysics;
- STARS: NOVAE