FIRST PHOTOMETRIC SOLUTION OF A VERY SHORT PERIOD CONTACT BINARY BELOW THE PERIOD LIMIT

Abstract

The star 1SWASP J022727.03+115641.7 was reported as a contact binary with a period shorter than the empirical limit of such systems. Our study shows the star not to be variable. Instead, it is the nearby star, 2MASS 02272637 +1156494, that exhibits variability. The BRI CCD light curves of 2MASS 02272637+1156494 show the system to be a moderate mass ratio (2.154(-0.008)(+0.074)), and shallow contact (10.4(-1.9)(+1.4)%) W-type contact binary. The masses, radii, and luminosities of the binary components are, respectively, M-1 = 0.25(-0.01)(+0.05), M-circle dot, M-2 = 0.54(-0.04)(+0.11) M-circle dot, R-1 = 0.45(-0.01)(+0.02) R-circle dot, R-2 = 0.063(-0.02)(+0.04) R-circle dot, L-1 = 0.038(-0.005)(+0.018) L-circle dot, and L-2 = 0.071(-0.010)(+0.037) L-circle dot, with an estimated distance 326(-46)(+127) pc. These uncertainties mainly come from the errors of the colors used to estimate the temperature of the primary star. A dark spot was introduced on the massive component in the final solution.