BVRI Photometric and Polarimetric studies of W UMa type Eclipsing Binary FO Hydra

TL;DR

This study analyzes optical photometric and polarimetric data of the contact binary FO Hydra, revealing its physical parameters, period increase, and low polarization levels, with implications for understanding W UMa systems.

Contribution

First detailed photometric and polarimetric analysis of FO Hydra, determining its physical parameters and polarization characteristics, and discussing potential causes of observed polarization.

Findings

FO Hya is a B-subtype W UMa contact binary.

The system's period is increasing at 5.77×10^{-8} days per year.

Polarization levels are lower than typical for W UMa binaries.

Abstract

We present analysis of optical photometric and polarimetric observations of contact binary system FO Hydra (FO Hya). The computed period of the system is 0.469556+/-0.000003 days. An O-C curve analysis indicates an increase in its period by 5.77x10^{-8} day yr^{-1}. The photometric light curves are analyzed using Wilson-Devinney code (WD). The present analysis shows that FO Hya is a B-subtype of W UMa type contact binary. The radii and mass of primary and secondary components are found, respectively, to be R_1 = 1.62+/-0.03 R_sun and R_2 = 0.91+/-0.02 R_sun, and M_1 = 1.31+/-0.07 M_sun and M_2 = 0.31+/-0.11 M_sun. The light curve shape shows small asymmetries around the primary and secondary maxima. This may be due to the presence of dark spots on the components. The polarimetric observations yield average values of its polarization to be 0.18+/-0.03, 0.15+/-0.03, 0.17+/-0.02 and 0.15+/-0.02 per cent in B, V, R and I bands, respectively. These values are appreciably lower than the typical polarization of W UMa type binaries. We have discussed the possible sources of the observed polarization but in order to arrive at definitive answer to this more phase locked observations are needed.