Both high precision CCD photometric and H$alpha$ line studies are presented for an overcontact binary ASAS J082243+1927.0. The light curve exhibits a total eclipse at secondary minima along with an OConnell effect. The light curve was modeled using t
he Wilson Devinney code and the best solution provides the mass ratio q = 0.106 and fill-out factor f = 72%. These parameters indicate that the system is a low mass ratio overcontact binary with a high degree of geometrical contact. The H alpha line equivalent width varied at different phases and it is found that the line is possibly filled-in at secondary minima. From a small sample of overcontact binaries, we found a correlation between the orbital period and H alpha line equivalent width of the primary component. Based on a sample of high filling factor and low mass ratio contact binaries, a mass ratio cut-off is observed at q = 0.085 in mass ratio - period plane. It was observed that below q $le$ 0.085, period decreases with an increase in q and above it, period increases as the mass ratio increases. Interestingly, the observed mass ratio cut-off value lies close to the critical mass ratio range as predicted in the literature. The observational evidence of the cut-off of the mass ratio and its variation with orbital period are discussed in terms of mass transfer and angular momentum loss. Based on the results, we suggest that, ASAS J082243+1927.0 is at the verge of merger, eventually forming a fast rotating star.
We present CCD photometric observations of an eclipsing binary in the direction of the open cluster Praesepe using the 2 m telescope of IUCAA Girawali Observatory, India. Though the system was classified as an eclipsing binary by Pepper et al.(2008),
detail investigations were lacking. The photometric solutions using the Wilson-Devinney code suggest that it is a W-type W UMa system and interestingly, the system parameters were similar to another contact binary system SW Lac.
