Long-term optical observations of Be/X-Ray binary system V0332+53

TL;DR

This study presents a long-term optical monitoring of the Be/X-ray binary V0332+53, revealing variability, disk changes, and spectral features that correlate with X-ray activity over nearly two decades.

Contribution

It provides the first detailed long-term optical variability and spectral analysis of V0332+53, linking optical disk behavior with X-ray activity and disk precession.

Findings

0.2 mag fading in optical brightness after MJD 53400

Single-peaked, symmetric Hα line profiles observed

Red-shifted Hα emission lines (~140 km/s) detected

Abstract

We have been monitoring the binary system V0332+53 (optical counterpart is BQ Cam) since 2004 using 45 cm ROTSEIIId telescope and RTT150 (Russian-Turkish 1.5 m Telescope) located at Bakirlitepe, Antalya, Turkey. We report on the long-term variability of this system up to the present date. There exists a fading of 0.2 mag in the light of BQ Cam after MJD 53400. The fading in the light curve of BQ Cam could be due to a decrease in the density or in the size of the circumstellar disk. We present optical spectroscopic observations obtained before (at MJD 54730) and during (at MJD 54768) the new X-ray activity reported by Krimm et al. (2008). The observed Ha line profiles were single-peaked and almost symmetric. The present EW values are found to be similar to the ones observed during the fading of infrared magnitudes of Negueruela et al. (1999). Ha emission lines were found to be red-shifted by ~140 km/s which were larger than the findings of Corbet et al. (1986). We suggest that brightening of the disk after MJD 54700 may be due to the precession of the disk.