Conservative mass transfer on eclipsing binary AE Phe from O-C diagram analysis

Abstract

Eclipsing binary is an edge-on binary system where the components appear to be eclipsing one another. Eclipsing binaries therefore give a lot of information on the systems’ behavior, one of them from their period change. O-C diagram exhibits the deviation of the observed time of minimum from the calculated ones and its analysis will reveal the responsible mechanism, such as a hidden third component, apsidal motion, and mass transfer. AE Phe (V = 8.15 mag and spectral class G0V) is a W UMa W-type binary. Previous studies of its degree of contact have revealed AE Phe to be a shallow-contact binary. Photometric data were taken using PROMPT (Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes), CTIO on October 4th, 2013 on four filters: B, V, R, and I. The Kwee and van Woerden (1956) method was also used to determine AE Phe’s time of minimum. Analysis of the O-C diagram (taken from 1975 toward our observation) suggest that the period of AE Phe shows a long-term continuous increase. These period increase and degree of contact suggest that AE Phe is undergoing thermal relaxation oscillation (TRO) and is evolving to a broken-contact phase, with a possibility of angular momentum loss (AML) through magnetic braking.