The light curve analyses and orbital period variations for two contact binary stars,LS Del and V997 Cyg,are presented in this work which was conducted in the frame of the Binary Systems of South and North project Grou...The light curve analyses and orbital period variations for two contact binary stars,LS Del and V997 Cyg,are presented in this work which was conducted in the frame of the Binary Systems of South and North project Ground-based photometric observations were performed at two observatories in France.We used the Transiting Exoplanet Survey Satellite(TESS)data for extracting times of minima and light curve analysis of the targe systems.The O-C diagram for both systems displays a parabolic trend.LS Del and V997 Cyg’s orbital periods are increasing at rates of dP/dt=7.20×10^(-08)days yr^(-1)and dP/dt=2.54×10^(-08)days yr^(-1),respectively Therefore,it can be concluded that mass is being transferred from the less massive star to the more massive component with a rate of dM/dt=-1.96×10^(-7)M_(⊙)yr^(-1)for the LS Del system,and dM/dt=-3.83×10^(-7)M_(⊙)yr-1for V997 Cyg.The parameters of a third possible object in the system are also considered.The PHysics Of Eclipsing BinariEs Python code was used to analyze the light curves.The light curve solutions needed a cold starspot due to the asymmetry in the LS Del system’s light curve maxima.The mass ratio fill-out factor,and star temperature all indicate that both systems are contact binary types in this investigation.Two methods were applied to estimate the absolute parameters of the systems:one method relied on the parallax of Gaia DR3,and the other used a P-M relationship.The positions of the systems are also depicted on the M-L,M-R q-L_(ratio),and logM_(tot)-logJ_(0)diagrams.We recommend that further observations and investigations be done on the existence of a fourth body in this system.展开更多
New multi-color BVRcIc photometric observations are presented for the W UMa type eclips- ing binary V1073 Cyg. The multi-color light curve analysis with the Wilson-Devinney procedure yielded the absolute parameters of...New multi-color BVRcIc photometric observations are presented for the W UMa type eclips- ing binary V1073 Cyg. The multi-color light curve analysis with the Wilson-Devinney procedure yielded the absolute parameters of this system, showing that V 1073 Cyg is a shallow contact binary system with a fill-out factor f = 0.124（±0.011）. We collected all available times of light minima spanning 119yr, including CCD data to construct the O - C curve, and performed detailed O - C analysis. The O - C diagram shows that the period change is complex. A long-term continuous decrease and a cyclic vari- ation exist. The period is decreasing at a rate ofP = -1.04（±0.18） × 10-10 d cycle-land, with the period decrease, V1073 Cyg will evolve to the deep contact stage. The cyclic variation with a period of P3 = 82.7（±3.6） yr and an amplitude of A = 0.028（±0.002） d may be explained by magnetic activ- ity of one or both components or the light travel time effect caused by a distant third companion with M3（i1 = 90°） = 0.511 M⊙.展开更多
Intensive photometric and spectral observations of the variable star V2551 Cyg are presented.The light curve shape reveals that the target is a pulsating star, contrary to its previous classification as an eclipsing b...Intensive photometric and spectral observations of the variable star V2551 Cyg are presented.The light curve shape reveals that the target is a pulsating star, contrary to its previous classification as an eclipsing binary. The period and amplitude of the light curve, the amplitudes of color changes and the radial velocity curve of V2551 Cyg are similar to those of a high-amplitude δ Scuti variable. The target seems to pulsate with the fundamental mode. However, V2551 Cyg exhibits several important peculiarities：（i） the decreasing branch of its light curve is steeper than the increasing one;（ii） the radial velocity curve has a flat section in the phase range 0.7-1.2 and short increase of the negative radial velocity at phase 0.7;（iii） the rotational velocity is quite big for a HADS star;（iv） the Fourier coefficients of V2551 Cyg are quite different from those of HADS stars. The target classification is difficult due to these peculiarities.展开更多
We present an analysis of the optical observations of Herbig Ae/Be(HAeBe)star V1686 Cyg,which is associated with a small isolated star-forming region around HAeBe star BD+40?4124.We observed this star as a part of our...We present an analysis of the optical observations of Herbig Ae/Be(HAeBe)star V1686 Cyg,which is associated with a small isolated star-forming region around HAeBe star BD+40?4124.We observed this star as a part of our project investigating young eruptive stars.Observations were conducted on the 2.6-m telescope of Byurakan Observatory from 2015 to 2017.In this period,we obtained direct images of V1686 Cyg and 14 medium-and low-resolution spectra.In the course of observations,we noticed that this star underwent an atypical brightness outburst.After data reduction,we found that the full rise and decline in the brightness of V1686 Cyg had an amplitude of almost 3 magnitudes and lasted about 3 months.We were also able to track changes in the stellar spectrum during the outburst,which are correlated with the photometric variations.展开更多
The eclipsing binary V2364 Cyg is an A7 V-type contact binary with a period of 0.5921 d.We present six spectra from LAMOST and BVRc light curves(LCs),which are simultaneously analyzed to obtain the absolute physical p...The eclipsing binary V2364 Cyg is an A7 V-type contact binary with a period of 0.5921 d.We present six spectra from LAMOST and BVRc light curves(LCs),which are simultaneously analyzed to obtain the absolute physical parameters.The first light maxima are brighter than the second ones by up to 0.m038,0.m036 and 0.m024 for BVRc bands,respectively.These distorted LCs are modeled by a cool spot on the less massive component.Its mass ratio and over-contact degree are q=0.319(±0.004) and f=28.4%(±1.0) % respectively.From the mass-luminosity diagram,the primary component is a normal main-sequence star,while the secondary one is a subgiant star.From the(O-C) curve,the orbital period secularly decreases at a rate dP/dt=-1.62(±0.03) × 10^-7 dyr^-1,which is mainly attributed to mass loss via stellar wind from the binary system.This may result in the observed infrared excess in the W4 band.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
Two eclipsing binary systems,UZ Lyr and BR Cyg,are semi-detached types whose secondary component fills its Roche lobe.Although radial velocity and light curves of these systems have already been investigated separatel...Two eclipsing binary systems,UZ Lyr and BR Cyg,are semi-detached types whose secondary component fills its Roche lobe.Although radial velocity and light curves of these systems have already been investigated separately,both their radial velocity and light curves are analyzed simultaneously for the first time in the present study.Also,the orbital period changes of these systems are studied.Our results show that the mass transfers between components have negligible effects on the orbital period changes of these systems,but two light travel time effects are the reasons for the periodic behavior of the O-C curve for UZ Lyr.We could not remark more information about orbital period changes for BR Cyg,but we find a new orbital period for it.By radial velocity and light curve analysis,we find a cold spot on the secondary component of BR Cyg.The new geometrical and physical parameters of both systems are obtained and their positions on the H-R diagram are demonstrated.展开更多
Dust extinction law is crucial to recover the intrinsic energy distribution of celestial objects and infer the characteristics of interstellar dust.Based on the traditional pair method,an improved pair method is propo...Dust extinction law is crucial to recover the intrinsic energy distribution of celestial objects and infer the characteristics of interstellar dust.Based on the traditional pair method,an improved pair method is proposed to model the dust extinguished spectral energy distribution(SED)of an individual star.Instead of the mathematically parameterizing extinction curves,the extinction curves in this work are directly from the silicate-graphite dust model,so that the dust extinction law can be obtained and the dust properties can be analyzed simultaneously.The ATLAS9 stellar model atmosphere is adopted for the intrinsic SEDs in this work,while the silicate-graphite dust model with a dust size distribution of dn da~a^(-a)exp(-a a_(c)),0.005<a<5μmfor each component is adopted for the model extinction curves.One typical extinction tracer in the dense region(V410 Anon9)and one in the diffuse region(Cyg OB2#12)of the Milky Way are chosen to test the reliability and the practicability of the improved pair method in different stellar environments.The results are consistent with their interstellar environments and are in agreement with the previous observations and studies,which prove that the improved pair method is effective and applicable in different stellar environments.In addition to the reliable extinction results,the derived parameters in the dust model can be used to analyze the dust properties,which cannot be achieved by other methods with the mathematical extinction models.With the improved pair method,the stellar parameters can also be inferred and the extinction law beyond the wavelengths of observed data can be predicted based on the dust model as well.展开更多
基金project was supported by the Scientific Research Projects Coordination Unit of Erciyes University(project number FBA-2022-11737)the TESS mission is provided by the NASA Explorer Program。
文摘The light curve analyses and orbital period variations for two contact binary stars,LS Del and V997 Cyg,are presented in this work which was conducted in the frame of the Binary Systems of South and North project Ground-based photometric observations were performed at two observatories in France.We used the Transiting Exoplanet Survey Satellite(TESS)data for extracting times of minima and light curve analysis of the targe systems.The O-C diagram for both systems displays a parabolic trend.LS Del and V997 Cyg’s orbital periods are increasing at rates of dP/dt=7.20×10^(-08)days yr^(-1)and dP/dt=2.54×10^(-08)days yr^(-1),respectively Therefore,it can be concluded that mass is being transferred from the less massive star to the more massive component with a rate of dM/dt=-1.96×10^(-7)M_(⊙)yr^(-1)for the LS Del system,and dM/dt=-3.83×10^(-7)M_(⊙)yr-1for V997 Cyg.The parameters of a third possible object in the system are also considered.The PHysics Of Eclipsing BinariEs Python code was used to analyze the light curves.The light curve solutions needed a cold starspot due to the asymmetry in the LS Del system’s light curve maxima.The mass ratio fill-out factor,and star temperature all indicate that both systems are contact binary types in this investigation.Two methods were applied to estimate the absolute parameters of the systems:one method relied on the parallax of Gaia DR3,and the other used a P-M relationship.The positions of the systems are also depicted on the M-L,M-R q-L_(ratio),and logM_(tot)-logJ_(0)diagrams.We recommend that further observations and investigations be done on the existence of a fourth body in this system.
基金partly supported by the National Natural Science Foundation of China(Nos.11573063,11325315 and U1631108)the Key Science Foundation of Yunnan Province(No.2017FA001)+1 种基金Chinese Academy of Sciences“Light of West China”Programthe research fund of Sichuan University of Science and Engineering(Grant No.2015RC42)
文摘New multi-color BVRcIc photometric observations are presented for the W UMa type eclips- ing binary V1073 Cyg. The multi-color light curve analysis with the Wilson-Devinney procedure yielded the absolute parameters of this system, showing that V 1073 Cyg is a shallow contact binary system with a fill-out factor f = 0.124（±0.011）. We collected all available times of light minima spanning 119yr, including CCD data to construct the O - C curve, and performed detailed O - C analysis. The O - C diagram shows that the period change is complex. A long-term continuous decrease and a cyclic vari- ation exist. The period is decreasing at a rate ofP = -1.04（±0.18） × 10-10 d cycle-land, with the period decrease, V1073 Cyg will evolve to the deep contact stage. The cyclic variation with a period of P3 = 82.7（±3.6） yr and an amplitude of A = 0.028（±0.002） d may be explained by magnetic activ- ity of one or both components or the light travel time effect caused by a distant third companion with M3（i1 = 90°） = 0.511 M⊙.
基金supported partly by project DN 08/20 of the Fund for Scientific Research of the Bulgarian Ministry of Education and Scienceproject RD 08-102 of Shumen University
文摘Intensive photometric and spectral observations of the variable star V2551 Cyg are presented.The light curve shape reveals that the target is a pulsating star, contrary to its previous classification as an eclipsing binary. The period and amplitude of the light curve, the amplitudes of color changes and the radial velocity curve of V2551 Cyg are similar to those of a high-amplitude δ Scuti variable. The target seems to pulsate with the fundamental mode. However, V2551 Cyg exhibits several important peculiarities：（i） the decreasing branch of its light curve is steeper than the increasing one;（ii） the radial velocity curve has a flat section in the phase range 0.7-1.2 and short increase of the negative radial velocity at phase 0.7;（iii） the rotational velocity is quite big for a HADS star;（iv） the Fourier coefficients of V2551 Cyg are quite different from those of HADS stars. The target classification is difficult due to these peculiarities.
基金supported by the RA MES State Committee of Science,in the frame of the research project number 18T-1C-329。
文摘We present an analysis of the optical observations of Herbig Ae/Be(HAeBe)star V1686 Cyg,which is associated with a small isolated star-forming region around HAeBe star BD+40?4124.We observed this star as a part of our project investigating young eruptive stars.Observations were conducted on the 2.6-m telescope of Byurakan Observatory from 2015 to 2017.In this period,we obtained direct images of V1686 Cyg and 14 medium-and low-resolution spectra.In the course of observations,we noticed that this star underwent an atypical brightness outburst.After data reduction,we found that the full rise and decline in the brightness of V1686 Cyg had an amplitude of almost 3 magnitudes and lasted about 3 months.We were also able to track changes in the stellar spectrum during the outburst,which are correlated with the photometric variations.
基金partially supported by the National Natural Science Foundation of China(Grant Nos.11873003&U1631108)Natural Science Research Key Program of Anhui Provincial Department of Education(No.KJ2019A0954)+1 种基金the Outstanding Young Talents Program of Anhui Provincial Department of Education(Nos.gxyq2018161&gxgnfx2019084)Open Project Program of the Key Laboratory of Optical Astronomy,National Astronomical Observatories,Chinese Academy of Sciences。
文摘The eclipsing binary V2364 Cyg is an A7 V-type contact binary with a period of 0.5921 d.We present six spectra from LAMOST and BVRc light curves(LCs),which are simultaneously analyzed to obtain the absolute physical parameters.The first light maxima are brighter than the second ones by up to 0.m038,0.m036 and 0.m024 for BVRc bands,respectively.These distorted LCs are modeled by a cool spot on the less massive component.Its mass ratio and over-contact degree are q=0.319(±0.004) and f=28.4%(±1.0) % respectively.From the mass-luminosity diagram,the primary component is a normal main-sequence star,while the secondary one is a subgiant star.From the(O-C) curve,the orbital period secularly decreases at a rate dP/dt=-1.62(±0.03) × 10^-7 dyr^-1,which is mainly attributed to mass loss via stellar wind from the binary system.This may result in the observed infrared excess in the W4 band.
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.
文摘Two eclipsing binary systems,UZ Lyr and BR Cyg,are semi-detached types whose secondary component fills its Roche lobe.Although radial velocity and light curves of these systems have already been investigated separately,both their radial velocity and light curves are analyzed simultaneously for the first time in the present study.Also,the orbital period changes of these systems are studied.Our results show that the mass transfers between components have negligible effects on the orbital period changes of these systems,but two light travel time effects are the reasons for the periodic behavior of the O-C curve for UZ Lyr.We could not remark more information about orbital period changes for BR Cyg,but we find a new orbital period for it.By radial velocity and light curve analysis,we find a cold spot on the secondary component of BR Cyg.The new geometrical and physical parameters of both systems are obtained and their positions on the H-R diagram are demonstrated.
基金supported by the National Natural Science Foundation of China(NSFC)through grant Nos.12133002,U2031209 and 12203025Shandong Provincial Natural Science Foundation through project ZR2022QA064the CSST Milky Way and Nearby Galaxies Survey on Dust and Extinction Project CMS-CSST2021-A09。
文摘Dust extinction law is crucial to recover the intrinsic energy distribution of celestial objects and infer the characteristics of interstellar dust.Based on the traditional pair method,an improved pair method is proposed to model the dust extinguished spectral energy distribution(SED)of an individual star.Instead of the mathematically parameterizing extinction curves,the extinction curves in this work are directly from the silicate-graphite dust model,so that the dust extinction law can be obtained and the dust properties can be analyzed simultaneously.The ATLAS9 stellar model atmosphere is adopted for the intrinsic SEDs in this work,while the silicate-graphite dust model with a dust size distribution of dn da~a^(-a)exp(-a a_(c)),0.005<a<5μmfor each component is adopted for the model extinction curves.One typical extinction tracer in the dense region(V410 Anon9)and one in the diffuse region(Cyg OB2#12)of the Milky Way are chosen to test the reliability and the practicability of the improved pair method in different stellar environments.The results are consistent with their interstellar environments and are in agreement with the previous observations and studies,which prove that the improved pair method is effective and applicable in different stellar environments.In addition to the reliable extinction results,the derived parameters in the dust model can be used to analyze the dust properties,which cannot be achieved by other methods with the mathematical extinction models.With the improved pair method,the stellar parameters can also be inferred and the extinction law beyond the wavelengths of observed data can be predicted based on the dust model as well.
