Photometric results of three δ Scuti stars, AD Ari, IP Vir and YZ Boo from new observations obtained at the:Xinglong Station of the Beijing Astronom- ical Observatory (BAO) during 2000 aELd 2001 are reported. We pres...Photometric results of three δ Scuti stars, AD Ari, IP Vir and YZ Boo from new observations obtained at the:Xinglong Station of the Beijing Astronom- ical Observatory (BAO) during 2000 aELd 2001 are reported. We present here the preliminary analyses. Detailed studies of these stars based on additional data will be published separately.展开更多
We present 145 times of light maximum for high amplitude δ Scuti star BO Lyn based on several sky surveys（CRTS,DASCH,NSVS,OMC and Super WASP）and our photometric observations.Combining with the data in literature,a ...We present 145 times of light maximum for high amplitude δ Scuti star BO Lyn based on several sky surveys（CRTS,DASCH,NSVS,OMC and Super WASP）and our photometric observations.Combining with the data in literature,a total of 179 times of light maximum are used to analyze the O-C diagram of BO Lyn.We find that it can be described by an upward parabolic component and a periodic variation with a period of 34.5±0.1 yr.The latter could be caused by the light travel time effect as a result of an additional companion orbiting in a highly elliptical orbit（e=0.64±0.03）.Our study indicates that the companion’s luminosity cannot be ignored,and it should be a late A-type main-sequence star.The long-term period change of BO Lyn is also detected,and its value,1.52±0.26×10^（-3）d Myr^（-1）,is consistent with evolutionary models.We suggest that more spectroscopic and photometric observations are needed in the future to confirm the nature of the BO Lyn system.展开更多
New V-band CCD observations of variable star V2455 Cyg were performed during two nights in September 2017. According to all times of maximum light and new maxima, the O-C curve was analyzed.The period changes of V2455...New V-band CCD observations of variable star V2455 Cyg were performed during two nights in September 2017. According to all times of maximum light and new maxima, the O-C curve was analyzed.The period changes of V2455 Cyg were investigated and the rate of increasing period was obtained to be(1/P) d P/dt = 1.99 × 10^-7 yr-1. Frequency analysis indicated that V2455 Cyg pulsates with the radial p mode and the fundamental frequency is 10.61574 d-1. Physical parameters of V2455 Cyg at mean temperature were determined(e.g., R = 2.52 R⊙and M = 1.92 M⊙). The position of this star in the H-R diagram confirms that V2455 Cyg is a high amplitude δ Scuti star.展开更多
Time-series photometry was made for the large-amplitude δ Scuff star AD CMi in 2005 and 2006. High-quality photometric data provided in the literature were used to analyze the pulsation of the star, with the derived ...Time-series photometry was made for the large-amplitude δ Scuff star AD CMi in 2005 and 2006. High-quality photometric data provided in the literature were used to analyze the pulsation of the star, with the derived multiple frequencies fitted to our new data. Besides the dominant frequency and its harmonics, one low frequency （2.27402 c d^-1） is discovered, which provides a reasonable interpretation for the long-noticed luminosity variation at the maximum and minimum light. Combining the nine new times of light maxima determined from the new data with the 64 times collected from the literature, we analyzed the long-term variability of AD CMi with the O - C technique. The results provide the updated value of period of 0.122974478 days, and seem to be in favor of the model of combination of the evolutionary effect and light-time effect of a binary system, of which some parameters are hereby deduced.展开更多
Time-series photometric observations were made for the high amplitudeδScuti star CW Ser between 2011 and 2012 at the Xinglong Station of National Astronomical Observatories,Chinese Academy of Sciences.After performin...Time-series photometric observations were made for the high amplitudeδScuti star CW Ser between 2011 and 2012 at the Xinglong Station of National Astronomical Observatories,Chinese Academy of Sciences.After performing the frequency analysis of the light curves,we confirmed the fundamental frequency of f=5.28677 c d 1,together with seven harmonics of the fundamental frequency,which are newly detected.No additional frequencies were detected.The O C diagram,produced with the 21 newly determined times of maximum light combined with those provided in the literature,helps to obtain a new ephemeris formula of the times of maximum light with the pulsation period of 0.189150355±0.000000003 d.展开更多
文摘Photometric results of three δ Scuti stars, AD Ari, IP Vir and YZ Boo from new observations obtained at the:Xinglong Station of the Beijing Astronom- ical Observatory (BAO) during 2000 aELd 2001 are reported. We present here the preliminary analyses. Detailed studies of these stars based on additional data will be published separately.
基金The DASCH project at Harvard is grateful for partial support from NSF grants AST-0407380,AST0909073 and AST-1313370partly supported by the West Light Foundation of Chinese Academy of Sciences+2 种基金the National Natural Science Foundation of China(Nos.11325315 and 11573063)the Yunnan Natural Science Foundation(Nos.2013FB084,2014FB187 and 2017FA001)the Strategic Priority Research Program “The Emergence of Cosmological Structures” of the Chinese Academy of Sciences(Grant No.XDB09010202)
文摘We present 145 times of light maximum for high amplitude δ Scuti star BO Lyn based on several sky surveys（CRTS,DASCH,NSVS,OMC and Super WASP）and our photometric observations.Combining with the data in literature,a total of 179 times of light maximum are used to analyze the O-C diagram of BO Lyn.We find that it can be described by an upward parabolic component and a periodic variation with a period of 34.5±0.1 yr.The latter could be caused by the light travel time effect as a result of an additional companion orbiting in a highly elliptical orbit（e=0.64±0.03）.Our study indicates that the companion’s luminosity cannot be ignored,and it should be a late A-type main-sequence star.The long-term period change of BO Lyn is also detected,and its value,1.52±0.26×10^（-3）d Myr^（-1）,is consistent with evolutionary models.We suggest that more spectroscopic and photometric observations are needed in the future to confirm the nature of the BO Lyn system.
基金supported by the Department of Physics,Payame Noor University,Tehran,Iran。
文摘New V-band CCD observations of variable star V2455 Cyg were performed during two nights in September 2017. According to all times of maximum light and new maxima, the O-C curve was analyzed.The period changes of V2455 Cyg were investigated and the rate of increasing period was obtained to be(1/P) d P/dt = 1.99 × 10^-7 yr-1. Frequency analysis indicated that V2455 Cyg pulsates with the radial p mode and the fundamental frequency is 10.61574 d-1. Physical parameters of V2455 Cyg at mean temperature were determined(e.g., R = 2.52 R⊙and M = 1.92 M⊙). The position of this star in the H-R diagram confirms that V2455 Cyg is a high amplitude δ Scuti star.
基金the National Natural Science Foundation of China
文摘Time-series photometry was made for the large-amplitude δ Scuff star AD CMi in 2005 and 2006. High-quality photometric data provided in the literature were used to analyze the pulsation of the star, with the derived multiple frequencies fitted to our new data. Besides the dominant frequency and its harmonics, one low frequency （2.27402 c d^-1） is discovered, which provides a reasonable interpretation for the long-noticed luminosity variation at the maximum and minimum light. Combining the nine new times of light maxima determined from the new data with the 64 times collected from the literature, we analyzed the long-term variability of AD CMi with the O - C technique. The results provide the updated value of period of 0.122974478 days, and seem to be in favor of the model of combination of the evolutionary effect and light-time effect of a binary system, of which some parameters are hereby deduced.
基金Supported by the National Natural Science Foundation of China (Grant No. U1231202)partially supported by the National Basic Research Program of China (973 Program, 2013CB834900)the Fundamental Research Funds for Central Universities
文摘Time-series photometric observations were made for the high amplitudeδScuti star CW Ser between 2011 and 2012 at the Xinglong Station of National Astronomical Observatories,Chinese Academy of Sciences.After performing the frequency analysis of the light curves,we confirmed the fundamental frequency of f=5.28677 c d 1,together with seven harmonics of the fundamental frequency,which are newly detected.No additional frequencies were detected.The O C diagram,produced with the 21 newly determined times of maximum light combined with those provided in the literature,helps to obtain a new ephemeris formula of the times of maximum light with the pulsation period of 0.189150355±0.000000003 d.
