A Photometric Investigation of the Short-Period Eclipsing Binary, Nova DQ Herculis (1934).

Nova DQ Her (1934) has been found to be an eclipsing binary having the shortest known period, 4li39 During 1954,1530 photoelectric observations of the system in three colors were obtained with the 100-inch Mount Wilson reflector. They indicate that, like UX UMa, the light-curve is of the Algol type, primary eclipse is partial, and no secondary eclipse is visible. Unlike UX UMa, the depth of primary decreases with decreasing wave length Other similarities to UX UMa include a minimum in the light- curve at 0 7P, occasional shoulders before and after eclipse, asymmetry of the rising branch of the eclipse-curve, and irregular intrinsic variations A unique feature of the light-curve of DQ Her is the occurrence between phases 0 1 lOP and 0 32SF of rapid variations in light having a period of 1180 minutes and a range of 0 07 mag in the ultraviolet. Provisional photometric elements have been derived for the system. The radii of the stars are about 0 10 Ro, while their masses are abnormally low, about 6 X 10- mo. It is possible that the low mass of the secondary star results from various observational errors and that the star is actually a normal M-type dwarf However, unless the system is so abnormal that the photometric elements have no meaning, the mass of the nova component must be very much less than the usually assumed value of 1 5 mo The resemblances between the light-curves of DQ Her and UX UMa suggest that tht peculiarities of both systems may be explained by a similar model