A Multicolour Photometric Study of the neglected eclipsing binary FT Ursae Majoris

Abstract

The multicolour photometric observations of the neglected eclipsing binary FT Ursae Majoris (FT UMa) were obtained in 2010. The 2003 version of Wilson-Devinney code was used to analyze the light curves in $B$, $V$, and $R$ bands simultaneously. Based on the spectroscopic mass ratio $q=0.984$ published by Pribulla et al., it is found that FT UMa is an evolved contact binary with a contact degree of 15.3%. The low amplitude of light variations, $\sim 0.15$ mag, arises mainly from a moderately low inclination angle of $i=62.^{\circ}80$ and almost identical components in size rather than the light dilution of a third component, which contributes light of only $\sim 10%$