Physical Structure of W Uma Binary System LO Andromeda

Abstract

The aims of this research were to study the orbital period change, parameter analize and its evolution of W Uma binary system LO Andromeda. The data gathering were done via CCD Photometer (SBIG ST10-XME) that attached to the 0.5 m - reflecting telescope of Princess Sirindhron Observatory, Chiang Mai University. The light curves obtained through B, V and R filters on UVB standard system were collected and processed via MaxIm DL4 softwere. The three times of minimum (2 primary eclipes and 1 secoundary eclipe) were determined. The result has shown that the new ephemeris equation from this research is HJD (Min) =
2453655.45049 + 0.38082E and the light curve has shown that the orbital period of LO Andromeda was 0.38082378 day. Calculated data, the orbital period change was +3.96238 x 10^-10 day/cycle or 0.00189048 sec/year. While, the best parameter by WD Program was 2.15947 of mass ratio and inclination was 89.45⁰. The temperature of primary star and secoundary star were 5250 K and 5252 K respectively. The binary system has shown that it is a KW type for H – R diagram. The best parameter was employed to make the model via a binary Maker 3.0 software. Finally, the result has represented that LO Andromeda is on the over contact phase but it still
hold the W Uma type.