We report B, V and R band CCD photometry of the Seyfert galaxy NGC 4151 obtained with the 1.0m telescope at Weihai Observatory of Shandong University and the 1.56 m telescope at Shanghai Astronomical Observatory from ...We report B, V and R band CCD photometry of the Seyfert galaxy NGC 4151 obtained with the 1.0m telescope at Weihai Observatory of Shandong University and the 1.56 m telescope at Shanghai Astronomical Observatory from 2005 December to 2013 February. Combining all available data from literature, we have constructed a historical light curve from 1910 to 2013 to study the periodicity of the source using three different methods （the Jurkevich method, the Lomb-Scargle periodogram method and the Discrete Correlation Function method）. We find possible periods of P1 = 4 ± 0.1,/92 = 7.5 ±0.3 and P3 = 15.9± 0.3 yr.展开更多
For the bright neutron star low-mass X-ray binary Sco X-l, we analyzed all updated frequencies of the twin kilohertz quasi-periodic oscillations （kHz QPOs）, their correlations and distributions. We found that the fr...For the bright neutron star low-mass X-ray binary Sco X-l, we analyzed all updated frequencies of the twin kilohertz quasi-periodic oscillations （kHz QPOs）, their correlations and distributions. We found that the frequency separation of the kHz QPO peaks appears not to be a constant, rather, it decreases with increasing inferred mass accretion rate. We show that the currently available data of Sco X-1 by Rossi X-ray Timing Explorer are inconsistent with the proposals of the beat model that the frequency separation is a constant. Our conclusions are consistent with those of some previous researchers and we discuss further implications for the kilohertz QPO models.展开更多
基金supported by the National Natural Science Foundation of China (Nos.11203016,11143012,10778619,10778701 and 10903005)the Natural Science Foundation of Shandong Province (No.ZR2012AQ008)
文摘We report B, V and R band CCD photometry of the Seyfert galaxy NGC 4151 obtained with the 1.0m telescope at Weihai Observatory of Shandong University and the 1.56 m telescope at Shanghai Astronomical Observatory from 2005 December to 2013 February. Combining all available data from literature, we have constructed a historical light curve from 1910 to 2013 to study the periodicity of the source using three different methods （the Jurkevich method, the Lomb-Scargle periodogram method and the Discrete Correlation Function method）. We find possible periods of P1 = 4 ± 0.1,/92 = 7.5 ±0.3 and P3 = 15.9± 0.3 yr.
文摘For the bright neutron star low-mass X-ray binary Sco X-l, we analyzed all updated frequencies of the twin kilohertz quasi-periodic oscillations （kHz QPOs）, their correlations and distributions. We found that the frequency separation of the kHz QPO peaks appears not to be a constant, rather, it decreases with increasing inferred mass accretion rate. We show that the currently available data of Sco X-1 by Rossi X-ray Timing Explorer are inconsistent with the proposals of the beat model that the frequency separation is a constant. Our conclusions are consistent with those of some previous researchers and we discuss further implications for the kilohertz QPO models.
