As an eclipsing polar with a 3.39 h orbital period, MN Hya was going through a state change when we observed it during 2009-2016. Ten new mid-eclipse times, along with others obtained from literature, allow us to give...As an eclipsing polar with a 3.39 h orbital period, MN Hya was going through a state change when we observed it during 2009-2016. Ten new mid-eclipse times, along with others obtained from literature, allow us to give a new ephemeris. The residuals of a linear fit show that period decreased during the phase of state change, which means angular momentum was lost during this phase. The associated X-ray observation indicates the mass accretion rate was about 3.6 x 10^-9 Mo yr^-1. The period decrease indicates that at least 60% of mass being transferred from the secondary was lost, maybe in the form of spherically symmetric stellar wind. In the high state, the data show the intensity of flickering reduced when the system had a higher accretion rate, and that flickering sticks out with a primary timescale of about 2 min, which implies the position of the threading point was about 30 white dwarf radii above its surface. The trend of light curves for the system in its high state follows that of the low state for a large fraction of the phase interval from phase 0 to phase 0.4 since, starting at phase 0.4, the cyclotron feature is visible, and the primary intensity hump of the light curves near phase 0.7 when the system is in the high state did not appear on the curve when it was in the low state. Those facts contradict predictions of the two-pole model.展开更多
通过对吐鲁番农业气象试验站2006年3月～11月 HYA-SF 土壤水分自动监测站和土钻法测定的土壤水分资料进行对比和相关分析,结果表明:两种土壤水分在垂直动态分布上较为一致、在时间动态变化上,受5 cm～80 cm 月平均地温的影响;5 cm～50 ...通过对吐鲁番农业气象试验站2006年3月～11月 HYA-SF 土壤水分自动监测站和土钻法测定的土壤水分资料进行对比和相关分析,结果表明:两种土壤水分在垂直动态分布上较为一致、在时间动态变化上,受5 cm～80 cm 月平均地温的影响;5 cm～50 cm 土壤水分在5 cm～80 cm 月平均地温≥25.0℃时,在不同的水平信度上具有较好的相关性。展开更多
We investigate orbital period changes of two deep, low mass ratio（DLMR） overcontact W UMa-type binaries, FG Hya and GR Vir. It is found that the orbital period of FG Hya shows a cyclic change with a period of Pmod= ...We investigate orbital period changes of two deep, low mass ratio（DLMR） overcontact W UMa-type binaries, FG Hya and GR Vir. It is found that the orbital period of FG Hya shows a cyclic change with a period of Pmod= 54.44 yr. The cyclic oscillation may be due to a third body in an eccentric orbit, while the orbital period of GR Vir shows a periodic variation with a period of Pmod= 28.56 yr and an amplitude of A = 0.0352 d. The periodic variation of GR Vir can be interpreted as a result of either the light-time effect of an unseen third body or the magnetic activity cycle.展开更多
New photometry for two Algol-type binaries, 0.8065 d）, was carried out using the 60-cm telescope EU Hya （P = 0.7782 d） and AW Vul （P = at Xinglong station of National Astronomical Observatories, Chinese Academy of...New photometry for two Algol-type binaries, 0.8065 d）, was carried out using the 60-cm telescope EU Hya （P = 0.7782 d） and AW Vul （P = at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. With the updated Wilson-Devinney code, photometric el- ements were derived from the multi-color light curves. The modeled results indicate that the two systems are near-contact binaries, whose secondary components fill their Roche lobes. The fill-out factors of the primaries are fp = 81.2 （±0.2）% for EU Hya and fp --- 82.4 （±0.3）% for AW Vul. Period analysis implies that there exists a downward parabola with a light-time orbit from the （O - C） curve. This kind of periodic oscillation may be attributed to the light-time orbit effect of a third companion. The long-term period de- crease may be caused by mass and angular momentum loss. When the orbital period decreases, the fill-out factor of fp will increase. Our results indicate that the primaries will also eventually fill their Roche lobes. EU Hya and AW Vul may possibly evolve from semi-detached binaries into contact ones.展开更多
Orbital period variations of the Algol-type eclipsing binary, VW Hydrae, are analyzed based on one newly determined eclipse time and the other times of light minima collected from the literature. It is discovered that...Orbital period variations of the Algol-type eclipsing binary, VW Hydrae, are analyzed based on one newly determined eclipse time and the other times of light minima collected from the literature. It is discovered that the orbital period shows a continuous increase at a rate ofdP/dt = ＋6.34 × 10^-7 d yr^-1 while it undergoes a cyclic change with an amplitude of 0.0639 d and a period of 51.5 yr. After the long-term period increase and the large-amplitude period oscillation were subtracted from the O-C curve, the residuals of the photoelectric and CCD data indicate a small-amplitude cyclic variation with a period of 8.75 yr and a small amplitude of 0.0048 d. The continuous period increase indicates a conservative mass transfer at a rate of dM2/dt = 7.89 × 10^-8 M⊙ yr^-1 from the secondary to the primary. The period increase may be caused by a combination of the mass transfer from the secondary to the primary and the angular momentum transfer from the binary system to the circumbinary disk. The two cyclic period oscillations can be explained by light-travel time effects via the presence of additional bodies. The small-amplitude periodic change indicates the existence of a less massive component with mass M3 〉 0.53 M⊙, while the large-amplitude one is caused by the presence of a more massive component with mass M4 〉 2.84M⊙. The ultraviolet source in the system reported by Kviz ＆ Rufener （1987） may be one of the additional components, and it is possible that the more massive one may be an unseen neutron star or black hole. The rapid period increase and the possibility of the presence of two additional components in the binary make it a very interesting system to study. New photometric and high-resolution spectroscopic observations and a detailed investigation of those data are required in the future.展开更多
This paper is devoted to binary stars belonging to the class of eclipsing-variable systems.Photometric and spectroscopic analysis of eclipses allows us to determine geometric parameters of the orbit and physical chara...This paper is devoted to binary stars belonging to the class of eclipsing-variable systems.Photometric and spectroscopic analysis of eclipses allows us to determine geometric parameters of the orbit and physical characteristics of stellar components as well as inclinations of stellar equators to the orbital plane. Estimations of inclinations can be obtained from measurement of the Rossiter-McLaughlin effect, which is discussed using examples of some eccentric binaries with an anomalous apsidal effect. Our task is to find the complete spectrum of solutions of the equation of apsidal motion, depending on the inclinations of the polar axes of the components to the orbital one for these systems, based on their individual spectroscopic and photometric observational data. The matrix of solutions allows us to select those pairs of polar inclinations that provide agreement with the observational apsidal period.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11325315,11611530685,11573063 and 11133007)the Strategic Priority Research Program the Emergence of Cosmological Structure of the Chinese Academy of Sciences(Grant No.XDB09010202)the Ministry of Education,Youth and Sports of the Czech Republic(Project LG15010)
文摘As an eclipsing polar with a 3.39 h orbital period, MN Hya was going through a state change when we observed it during 2009-2016. Ten new mid-eclipse times, along with others obtained from literature, allow us to give a new ephemeris. The residuals of a linear fit show that period decreased during the phase of state change, which means angular momentum was lost during this phase. The associated X-ray observation indicates the mass accretion rate was about 3.6 x 10^-9 Mo yr^-1. The period decrease indicates that at least 60% of mass being transferred from the secondary was lost, maybe in the form of spherically symmetric stellar wind. In the high state, the data show the intensity of flickering reduced when the system had a higher accretion rate, and that flickering sticks out with a primary timescale of about 2 min, which implies the position of the threading point was about 30 white dwarf radii above its surface. The trend of light curves for the system in its high state follows that of the low state for a large fraction of the phase interval from phase 0 to phase 0.4 since, starting at phase 0.4, the cyclotron feature is visible, and the primary intensity hump of the light curves near phase 0.7 when the system is in the high state did not appear on the curve when it was in the low state. Those facts contradict predictions of the two-pole model.
文摘通过对吐鲁番农业气象试验站2006年3月～11月 HYA-SF 土壤水分自动监测站和土钻法测定的土壤水分资料进行对比和相关分析,结果表明:两种土壤水分在垂直动态分布上较为一致、在时间动态变化上,受5 cm～80 cm 月平均地温的影响;5 cm～50 cm 土壤水分在5 cm～80 cm 月平均地温≥25.0℃时,在不同的水平信度上具有较好的相关性。
基金supported by the National Natural Science Foundation of China(Grant No.11703020)Joint Research Funds in Astronomy(U1531108,U1731106 and U1731110)under cooperative agreement between the National Natural Science Foundation of China and Chinese Academy of Sciences
文摘We investigate orbital period changes of two deep, low mass ratio（DLMR） overcontact W UMa-type binaries, FG Hya and GR Vir. It is found that the orbital period of FG Hya shows a cyclic change with a period of Pmod= 54.44 yr. The cyclic oscillation may be due to a third body in an eccentric orbit, while the orbital period of GR Vir shows a periodic variation with a period of Pmod= 28.56 yr and an amplitude of A = 0.0352 d. The periodic variation of GR Vir can be interpreted as a result of either the light-time effect of an unseen third body or the magnetic activity cycle.
基金support from the National Natural Science Foundation of China under grant Nos.11473009 and U1131102the Open Research Program Foundation(No.OP 201110)
文摘New photometry for two Algol-type binaries, 0.8065 d）, was carried out using the 60-cm telescope EU Hya （P = 0.7782 d） and AW Vul （P = at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. With the updated Wilson-Devinney code, photometric el- ements were derived from the multi-color light curves. The modeled results indicate that the two systems are near-contact binaries, whose secondary components fill their Roche lobes. The fill-out factors of the primaries are fp = 81.2 （±0.2）% for EU Hya and fp --- 82.4 （±0.3）% for AW Vul. Period analysis implies that there exists a downward parabola with a light-time orbit from the （O - C） curve. This kind of periodic oscillation may be attributed to the light-time orbit effect of a third companion. The long-term period de- crease may be caused by mass and angular momentum loss. When the orbital period decreases, the fill-out factor of fp will increase. Our results indicate that the primaries will also eventually fill their Roche lobes. EU Hya and AW Vul may possibly evolve from semi-detached binaries into contact ones.
基金Supported by the National Natural Science Foundation of China.
文摘Orbital period variations of the Algol-type eclipsing binary, VW Hydrae, are analyzed based on one newly determined eclipse time and the other times of light minima collected from the literature. It is discovered that the orbital period shows a continuous increase at a rate ofdP/dt = ＋6.34 × 10^-7 d yr^-1 while it undergoes a cyclic change with an amplitude of 0.0639 d and a period of 51.5 yr. After the long-term period increase and the large-amplitude period oscillation were subtracted from the O-C curve, the residuals of the photoelectric and CCD data indicate a small-amplitude cyclic variation with a period of 8.75 yr and a small amplitude of 0.0048 d. The continuous period increase indicates a conservative mass transfer at a rate of dM2/dt = 7.89 × 10^-8 M⊙ yr^-1 from the secondary to the primary. The period increase may be caused by a combination of the mass transfer from the secondary to the primary and the angular momentum transfer from the binary system to the circumbinary disk. The two cyclic period oscillations can be explained by light-travel time effects via the presence of additional bodies. The small-amplitude periodic change indicates the existence of a less massive component with mass M3 〉 0.53 M⊙, while the large-amplitude one is caused by the presence of a more massive component with mass M4 〉 2.84M⊙. The ultraviolet source in the system reported by Kviz ＆ Rufener （1987） may be one of the additional components, and it is possible that the more massive one may be an unseen neutron star or black hole. The rapid period increase and the possibility of the presence of two additional components in the binary make it a very interesting system to study. New photometric and high-resolution spectroscopic observations and a detailed investigation of those data are required in the future.
文摘This paper is devoted to binary stars belonging to the class of eclipsing-variable systems.Photometric and spectroscopic analysis of eclipses allows us to determine geometric parameters of the orbit and physical characteristics of stellar components as well as inclinations of stellar equators to the orbital plane. Estimations of inclinations can be obtained from measurement of the Rossiter-McLaughlin effect, which is discussed using examples of some eccentric binaries with an anomalous apsidal effect. Our task is to find the complete spectrum of solutions of the equation of apsidal motion, depending on the inclinations of the polar axes of the components to the orbital one for these systems, based on their individual spectroscopic and photometric observational data. The matrix of solutions allows us to select those pairs of polar inclinations that provide agreement with the observational apsidal period.
