The first photometric analysis of the near contact binary IR Cas

TL;DR

This study presents the first detailed photometric analysis of IR Cas, revealing it as a near contact binary with evidence of a third body and ongoing mass transfer, indicating its potential evolution into a contact system.

Contribution

It provides the first photometric and orbital analysis of IR Cas, identifying its near contact nature and possible third body influence.

Findings

IR Cas is a near contact binary with the primary filling its Roche lobe.

Evidence of a third body causing periodic changes in the O-C diagram.

The system's period is decreasing due to mass transfer, suggesting evolution into a contact system.

Abstract

The first photometric analysis of IR Cas was carried out based on the new observed BVRI light curves. The symmetric light curves and nearly flat secondary minimum indicate that very precise photometric results can be determined. We found that IR Cas is a near contact binary with the primary component filling its Roche lobe. An analysis of the O-C diagram based on all available times of light minimum reveals evidence for a periodic change with a semiamplitude of 0.0153 days and a period of 39.7 years superimposed on a secular decrease at a rate of dp/dt=-1.28(\pm0.09)\times10^{-7} d yr^{-1}. The most reasonable explanation for the periodic change is the light time-travel effect due to a third body. The period decrease may be caused by mass transfer from the primary component to the secondary. With the decreasing period, IR Cas would eventually evolve into a contact system.