Abstract GSC 4560–02157 is a new eclipsing cataclysmic variable with an orbital period of 0.265359 days. By using the published V − and R−band data together with our observations, we discovered that the O − C curve of GSC 4560–02157 may show a cyclic variation with a period of 3.51 years and an amplitude of 1.40 min. If this variation is caused by a light travel-time effect via the existence of a third body, then its mass can be derived as M3sin i'≈ 91.08 MJup, and it should be a low-mass star. In addition, several physical parameters were measured. The color of the secondary star was determined to be V − R = 0.77(±0.03) which corresponds to a spectral type of K2–3. The secondary star’s mass was estimated as M2 = 0.73(±0.02) M⊙ by combing the derived V − R value around phase 0 with the assumption that it obeys the mass-luminosity relation for main sequence stars. This mass is consistent with the mass−period relation for CV donor stars. For the white dwarf, the eclipse durations and contacts of the white dwarf yield an upper limit on the white dwarf’s radius corresponding to a lower limit on mass of M1 ≈ 0.501 M⊙. The overestimated radius and previously published spectral data indicate that the boundary layer may have a very high temperature.
Keywords techniques: photometric — stars: binaries: cataclysmic variables — stars: individual: GSC 4560–02157
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