Investigation of superhumps in SU UMa-type dwarf novae based on the observations of TESS

Abstract

We report the superhumps analysis of seven SU UMa-type dwarf novae based on the observations of Transiting Exoplanet Survey Satellite (TESS). Superhumps are seen during superoutbursts of SU UMa-type dwarf novae. The month-long data sets of TESS are well suited for studying the variation of superhumps. We selected seven non-eclipsing SU UMa-type dwarf novae with superhumps in which TESS light curves are available and have not yet been studied. The stages A, B, and C of superhumps in superoutbursts were determined by O-C method. The results indicate that not all complete superoutbursts show obvious three stages, such as DT Oct and the second superoutburst of J1730+6247. We calculated the superhump periods for each stage and the mean periods for whole superoutbursts. Taking the stage A superhump method, the mass ratios (M2/M1) were estimated. According to the results, the seven stars are pre-bounce systems with mass ratios ranging from 0.1 to 0.2. By combining the orbital periods and the mean superhump periods, the precession periods were calculated. The results show that the precession periods of the seven SU UMa stars are about 2 days.