Photometric study of the overcontact binary V826 Aur

Abstract

We present BVR_C differential photometry of an eclipsing binary system V826 Aur. A period analysis shows near constant period of 0.36 days across two decades of observation. The best fit models are consistent with a W-type W UMa overcontact binary consisting of a less massive G8 primary star and a more massive K0 secondary star. The modeled system properties are unremarkable with mass ratio (q = 2 . 9), inclination (i = 82 °), fillout factor (f = 0 . 094), and temperature ratio (T₂ /T₁ = 0 . 96), all near the average for W-type systems. A very slight O'Connell effect is present and is analyzed. A cool spot is used to model the effect, resulting in fitted spot parameters of angular size (ρ = 8 . 2 °), temperature factor (κ = 0 . 81), and longitude (λ = 63 °) while colatitude was fixed at 90°.