We report a V band photometry of the SU UMa star IR Gem at quiescence in January 2002. The observations were made with two telescopes spaced ~ 160° apart in longitude. Several photometric modulations have been fo...We report a V band photometry of the SU UMa star IR Gem at quiescence in January 2002. The observations were made with two telescopes spaced ~ 160° apart in longitude. Several photometric modulations have been found. One gives a period of 98.50(13) min, exactly equal to the orbital period determined spectroscopically. Two others occasionally strengthen and seem to be positive and negative superhumps with periods of 103.6(4) and 95.4(4) min, 5.2 % longer and 3.1 % shorter than the orbital period, respectively. A signal at ~ 0.6 c/d in the power spectrum is roughly consistent with the expected period of nodal precession of the disk. There is a puzzling peak at 0.21(3) c/d corresponding to the ~ 4.3 d sine wave seen in the raw light curve. We suspect it to be a beat frequency between the frequencies of apsidal and nodal precessions of the disk. Quasi-periodic cycles with amplitudes 0.15–0.6 mag can be seen in the light curve. The mechanism underlying this modulation is not clear.展开更多
The near-contact binary UU Lyn with an F3V-type primary was observed in 2005 and 2006. With the latest version of the Wilson-Devinney code, the photometric elements were computed. The results reveal that UU Lyn is a m...The near-contact binary UU Lyn with an F3V-type primary was observed in 2005 and 2006. With the latest version of the Wilson-Devinney code, the photometric elements were computed. The results reveal that UU Lyn is a marginal contact system with a large temperature difference of about 1900 K between the primary and secondary components. All available eclipse times, including new ones, were used in the analysis. The results show that the orbital period of this system undergoes a continuous decrease at a rate of dP/dt = -1.84 × 10^-8 d yr^-1. With the period decrease, UU Lyn may evolve from the present shortperiod marginal contact system into a contact system with true thermal contact. This target might just be undergoing the cycles predicted by the theory of thermal relaxation oscillations （TRO）. It is an interesting example resembling BL And, GW Tau, ZZ Aur, KQ Gem, CN And and AD Cnc, that lie in the key evolutionary stage.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘We report a V band photometry of the SU UMa star IR Gem at quiescence in January 2002. The observations were made with two telescopes spaced ~ 160° apart in longitude. Several photometric modulations have been found. One gives a period of 98.50(13) min, exactly equal to the orbital period determined spectroscopically. Two others occasionally strengthen and seem to be positive and negative superhumps with periods of 103.6(4) and 95.4(4) min, 5.2 % longer and 3.1 % shorter than the orbital period, respectively. A signal at ~ 0.6 c/d in the power spectrum is roughly consistent with the expected period of nodal precession of the disk. There is a puzzling peak at 0.21(3) c/d corresponding to the ~ 4.3 d sine wave seen in the raw light curve. We suspect it to be a beat frequency between the frequencies of apsidal and nodal precessions of the disk. Quasi-periodic cycles with amplitudes 0.15–0.6 mag can be seen in the light curve. The mechanism underlying this modulation is not clear.
基金Supported by the National Natural Science Foundation of China.
文摘The near-contact binary UU Lyn with an F3V-type primary was observed in 2005 and 2006. With the latest version of the Wilson-Devinney code, the photometric elements were computed. The results reveal that UU Lyn is a marginal contact system with a large temperature difference of about 1900 K between the primary and secondary components. All available eclipse times, including new ones, were used in the analysis. The results show that the orbital period of this system undergoes a continuous decrease at a rate of dP/dt = -1.84 × 10^-8 d yr^-1. With the period decrease, UU Lyn may evolve from the present shortperiod marginal contact system into a contact system with true thermal contact. This target might just be undergoing the cycles predicted by the theory of thermal relaxation oscillations （TRO）. It is an interesting example resembling BL And, GW Tau, ZZ Aur, KQ Gem, CN And and AD Cnc, that lie in the key evolutionary stage.
