Orbital period changes of the W UMa-type binary YY Eri are analyzed by using all photoelectric and ccd times of light minimum. The results show that its orbital period is undergo- ing a secular increase superposed on ...Orbital period changes of the W UMa-type binary YY Eri are analyzed by using all photoelectric and ccd times of light minimum. The results show that its orbital period is undergo- ing a secular increase superposed on two cyclic oscillations. The continuous increase at the rate of dP/dt = 6.3806 × 10^-8 d yr^-1 may be accounted for by mass transfer from the less massive com- panion to the more massive one. Two periodic variations with periods of 38.6192 and 22.3573 yr may be attributed to the light-time effect of a faint third star and the cyclic magnetic activity of the system, respectively.展开更多
The periapsis shift of charged test particles in arbitrary static and spherically symmetric charged spacetimes are studied.Two perturbative methods,the near-circular approximation and post-Newtonian methods,are develo...The periapsis shift of charged test particles in arbitrary static and spherically symmetric charged spacetimes are studied.Two perturbative methods,the near-circular approximation and post-Newtonian methods,are developed and shown to be very accurate when the results are determined to high orders.The near-circular approximation method is more precise when eccentricity e of the orbit is small,whereas the post-Newtonian method is more effective when orbit semilatus rectum p is large.Results from these two methods are shown to agree when both e is small and p is large.These results are then applied to the Reissner-Nordström spacetime,the Einstein-Maxwell-dilation gravity,and a charged wormhole spacetime.The effects of various parameters on the periapsis shift,particularly that of the electrostatic interaction,are carefully studied.The periapsis shift data of the solar-Mercury are then used to constrain the charges of the Sun and Mercury,and the data of the Sgr A^(*)-S2 periapsis shift are used to determine,for the first time using this method,the constraints of the charges of Sgr A^(*)and S2.展开更多
基金supported by the Joint Research Funds in Astronomy (U1531108, U1731106 and U1731110)the National Natural Science Foundation of China and Chinese Academy of Sciencespartially supported by the National Natural Science Foundation of China (11703020)
文摘Orbital period changes of the W UMa-type binary YY Eri are analyzed by using all photoelectric and ccd times of light minimum. The results show that its orbital period is undergo- ing a secular increase superposed on two cyclic oscillations. The continuous increase at the rate of dP/dt = 6.3806 × 10^-8 d yr^-1 may be accounted for by mass transfer from the less massive com- panion to the more massive one. Two periodic variations with periods of 38.6192 and 22.3573 yr may be attributed to the light-time effect of a faint third star and the cyclic magnetic activity of the system, respectively.
基金Supported by the Wuhan University Research Development Fund。
文摘The periapsis shift of charged test particles in arbitrary static and spherically symmetric charged spacetimes are studied.Two perturbative methods,the near-circular approximation and post-Newtonian methods,are developed and shown to be very accurate when the results are determined to high orders.The near-circular approximation method is more precise when eccentricity e of the orbit is small,whereas the post-Newtonian method is more effective when orbit semilatus rectum p is large.Results from these two methods are shown to agree when both e is small and p is large.These results are then applied to the Reissner-Nordström spacetime,the Einstein-Maxwell-dilation gravity,and a charged wormhole spacetime.The effects of various parameters on the periapsis shift,particularly that of the electrostatic interaction,are carefully studied.The periapsis shift data of the solar-Mercury are then used to constrain the charges of the Sun and Mercury,and the data of the Sgr A^(*)-S2 periapsis shift are used to determine,for the first time using this method,the constraints of the charges of Sgr A^(*)and S2.
