We present a comprehensive analysis of BI CVn,an eclipsing overcontact binary system.New BVR photometric observations,combined with available spectroscopic data,were analyzed simultaneously using the Wilson–Devinney ...We present a comprehensive analysis of BI CVn,an eclipsing overcontact binary system.New BVR photometric observations,combined with available spectroscopic data,were analyzed simultaneously using the Wilson–Devinney method to derive the orbital and physical parameters of the system.The resulting stellar parameters are M1=0.58±0.01M⊙,M2=1.42±0.02M⊙,R1=0.88±0.01R⊙,R2=1.31±0.01R⊙,with an orbital separation of a=2.80±0.01R⊙.Based on all available CCD times of minimum light,including both ground-based and T ESS observations,the(O-C)diagram of BI CVn was analyzed.T he orbital period exhibits a long-term decrease at a rate of-2.3239(±0.0001)×10-8 day yr-1,likely due to mass transfer from the more massive to the less massive component.Superimposed on this trend is a cyclic variation with a period of 56.84±0.08 yr,indicative of a light-travel time effect caused by a third body,whose estimated mass is 0.63±0.02M⊙.Using these derived parameters,we modeled the binary’s evolution through non-conservative processes with the Binary Star Evolution code.The evolutionary tracks of the components were examined in multiple parameter planes,leading to an estimated merger timescale of approximately 2.70 Gyr.展开更多
The action of gravitons in a binary star system is modelled as the locus of points on an ellipse synchronous to the elliptic orbit of the binary star. In their interaction between the masses in the system the rotation...The action of gravitons in a binary star system is modelled as the locus of points on an ellipse synchronous to the elliptic orbit of the binary star. In their interaction between the masses in the system the rotational energy of the gravitons is reduced by gravitational redshift, which accounts for the decay of the binary star orbital period. This model is able to fit a broad range of eccentricities of binary pulsar orbits and orbital period decay comparable to the General Relativistic gravitational wave model.展开更多
We present a detailed analysis of a double-lined spectroscopic binary system,Bo Gem,using data obtained from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)and the Transiting Exoplanet Survey Sat...We present a detailed analysis of a double-lined spectroscopic binary system,Bo Gem,using data obtained from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)and the Transiting Exoplanet Survey Satellite(TESS).By applying spectral disentangling techniques to the LAMOST Medium Resolution Spectra,we determine the orbital parameters,including the orbital period of P=4.0689 days,and semimajor axis of a=14.90±0.04 R_(⊙).The mass ratio between the two components is found to be q=0.198±0.006,with an inclination of i=82°.3±0°.13.The photometric data from TESS revealed periodic light variations due to the eclipsing nature of the system,allowing for the determination of the primary star’s radius as R_(1)=1.68±0.03 R_(⊙)and the secondary star’s radius as R_(2)=3.68±0.04 R_(⊙).The effective temperatures of the primary and secondary stars are measured to be T_(eff,1)=9705±50 K and T_(eff,2)=5830±22 K,respectively.By analyzing the disentangled spectra,we determined the stellar atmospheric parameters—including surface gravity and metallicity of both stars.These results not only confirm the double-lined spectroscopic binary status of Bo Gem,but also underscore its value as an important system for testing and refining stellar evolution models.展开更多
Al-Wardat's method is used in this research to analyze the two components of the HD 25811 binary system,which combines the results of speckle interferometry with the astrometric data to construct the synthetic spe...Al-Wardat's method is used in this research to analyze the two components of the HD 25811 binary system,which combines the results of speckle interferometry with the astrometric data to construct the synthetic spectral energy distribution of the system.The method results in the effective temperatures at 7100±50 K for component A and 7000±50 K for component B,while their masses measure as 1.65±0.15M_(⊙)for component A and1.58±0.14M_(⊙)for component B.The system exists at an estimated age of 0.794 Gyr,while both stars remain in their initial subgiant evolutionary phase.The evolutionary tracks together with isochrones for Z=0.03 validate that the system components share both their origin and chemical compositions.The orbital analysis shows that the system has a period of 15.97 yr and an eccentricity of 0.713,while the total system mass amounts to3.65±0.49 M_(⊙).We detailedly analyze the system's orbital dynamics to assess planetary stability and habitability zones,which lead to the dynamics of circumbinary(P-type)and circumstellar(S-type)orbits using empirical criteria,revealing large regions in which planetary orbits remain dynamically stable.Luminosities and effective temperatures of each stellar component are used to determine their habitable zones.展开更多
Based on positional observations and measurements of radial velocities,the orbits of 850 wide visual binary stars have been determined.The parameters of the log-normal distributions for the histograms of orbital perio...Based on positional observations and measurements of radial velocities,the orbits of 850 wide visual binary stars have been determined.The parameters of the log-normal distributions for the histograms of orbital periods,stellar masses,and semimajor axes in astronomical units have been obtained.The eccentricity histogram for binary stars with orbital periods less than 400 yr follows a normal distribution centered at e=0.545+/−0.029.For stars with longer periods,this distribution obeys the law f=2e,with accuracy to errors.The mass-to-luminosity relation for stars with well-determined masses is given by:log L_(⊙)=4.33 logM_(⊙)-0.11,where L_(⊙) and M_(⊙) are the luminosity and mass of the star in units of the solar luminosity and mass,respectively.展开更多
Most massive stars reside in binary or multi-object systems.Short gamma-ray bursts(sGRBs),the product of the merger of double compact objects,may originate from massive common-envelope binaries.In contrast,the progeni...Most massive stars reside in binary or multi-object systems.Short gamma-ray bursts(sGRBs),the product of the merger of double compact objects,may originate from massive common-envelope binaries.In contrast,the progenitors of long GRBs(lGRBs)are typically considered isolated massive stars.However,no effective method has yet been established to identify potential companions from current observations.Recent studies have demonstrated that quasi-periodic oscillation signatures can serve as a promising tool to probe the properties of GRB central engines.In this study,by drawing an analogy to periodicity in X-ray binaries,we explore the precession periods of companion-induced disk precession for lGRBs born in the ultra-compact binary scenario.Our results suggest that the periodicity observed in lGRB afterglows,measured in units of 1000 s or more,may indicate that lGRBs originate within binary systems.GRB 050904 could represent a rare case where the burst occurred in a binary system,leaving behind a black hole–black hole binary at redshift z=6.29.展开更多
AR Aur A+B is a close binary of astrophysical interest because dissimilar surface compositions are reported between similar late B-type dwarfs.A new spectroscopic study on this system was carried out based on the dise...AR Aur A+B is a close binary of astrophysical interest because dissimilar surface compositions are reported between similar late B-type dwarfs.A new spectroscopic study on this system was carried out based on the disentangled spectra,in order to determine their atmospheric parameters and elemental abundances.The effective temperature and microturbulence(determined from the equivalent widths of Fe II lines)turned out to be(11,150 K,0.9 km s^(-1))and(10,650 K,0.1 km s^(-1))for A and B,respectively.The chemical abundances of 28 elements were then derived while taking into account the non-LTE effect for Z≤15 elements(Z:atomic number).The following trends were elucidated for[X/H](abundance of X relative to the Sun):(1)Qualitatively,[X/H]shows a rough global tendency to increase with Z,with the gradient steeper for A than for B.(2)However,considerable dispersion is involved for A,since prominently large peculiarities are seen in specific elements reflecting the characteristics of HgMn stars(e.g.,very deficient N,Al,Sc,Ni;markedly overabundant P,Mn).(3)In contrast,the Z-dependence of[X/H]for B tends to be nearly linear with only a small dispersion.These observational facts may serve as a key to understanding the critical condition for the emergence of the chemical anomaly.展开更多
We investigate the exchange of mass in a binary system as a channel through which a Be star can receive a rapid rotation.The mass-transfer phase in a massive close binary system in the Hertzsprung-gap is accompanied b...We investigate the exchange of mass in a binary system as a channel through which a Be star can receive a rapid rotation.The mass-transfer phase in a massive close binary system in the Hertzsprung-gap is accompanied by the spinning up of the accreting component.We consider a case when the mass of the accreting component increases by 1.5 times.The component acquires mass and angular momentum while in a state of critical rotation.The angular momentum of the component increases by 50 times.Meridional circulation effectively transports angular momentum inside the component during the mass-transfer phase and during the thermal timescale after the end of the mass-transfer phase.As a result of mass transfer,the component acquires the rotation typical of classical Be stars.展开更多
This paper investigates the spin-up of a mass-accreting star in a close binary system passing through the first stage of mass exchange in the Hertzsprung gap. Inside an accreting star, angular momentum is carried by m...This paper investigates the spin-up of a mass-accreting star in a close binary system passing through the first stage of mass exchange in the Hertzsprung gap. Inside an accreting star, angular momentum is carried by meridional circulation and shear turbulence. The circulation carries part of the angular momentum of the accreted layers to the accretor's surface. The greater the rate of arrival of angular momentum in the accretor is, the greater this part. It is assumed that this part of the angular momentum can be removed by the disk further from the accretor. If the angular momentum in the matter entering the accretor is more than half the Keplerian value, then the angular momentum obtained by the accretor during mass exchange stage does not depend on the rate of arrival of angular momentum. The accretor may have the characteristics of a Be-star immediately after the end of mass exchange.展开更多
The existence of pulsating stars in eclipsing binaries has been known for decades.These types of objects are extremely valuable systems for astronomical studies as they exhibit both eclipse and pulsation variations.Th...The existence of pulsating stars in eclipsing binaries has been known for decades.These types of objects are extremely valuable systems for astronomical studies as they exhibit both eclipse and pulsation variations.The eclipsing binaries are the only way to directly measure the mass and radius of stars with a good accuracy(≤1%),while the pulsations are a unique way to probe the stellar interior via oscillation frequencies.There are different types of pulsating stars existing in eclipsing binaries.One of them is theδScuti variables.Currently,the known number ofδScuti stars in eclipsing binaries is around 90 according to the latest catalog of these variables.An increasing number of these kinds of variables is important to understand the stellar structure,evolution and the effect of binarity on the pulsations.Therefore,in this study,we focus on discovering new eclipsing binaries withδScuti component(s).We searched within the northern Transiting Exoplanet Survey Satellite(TESS)field with a visual inspection by following some criteria such as light curve shape,the existence of pulsation like variations in the out-of-eclipse light curve and the T_(eff) values of the targets.As a result of these criteria,we discovered some targets.The orbital variations were first removed from the TESS light curves and frequency analysis was performed on the residuals.The luminosity,and absolute and bolometric magnitudes of the targets were calculated as well.To find how much of these parameters represent the primary(more luminous)binary component,we also computed the flux density ratio of the systems by utilizing the area of the eclipses.In addition,the positions of the systems in the H-R diagram were examined considering the flux density ratios.As a consequence of the investigation,we defined 38 candidateδScuti stars and also one Maia variable in eclipsing binary systems.展开更多
Three important physical processes occurring in contact binary systems are studied. The first one is the effect of spin, orbital rotation and tide on the structure of the components, which includes also the effect of ...Three important physical processes occurring in contact binary systems are studied. The first one is the effect of spin, orbital rotation and tide on the structure of the components, which includes also the effect of meridian circulation on the mixing of the chemical elements in the components. The second one is the mass and energy exchange between the components. To describe the energy exchange, a new approach is introduced based on the understanding that the exchange is due to the release of the potential, kinetic and thermal energy of the exchanged mass. The third is the loss of mass and angular momentum through the outer Lagrangian point. The rate of mass loss and the angular momentum carded away by the lost mass are discussed. To show the effects of these processes, we follow the evolution of a binary system consisting of a 12M⊙ and a 5M⊙ star with mass exchange between the components and mass loss via the outer Lagrangian point, both with and without considering the effects of rotation and tide. The result shows that the effect of rotation and tide advances the start of the semi-detached and the contact phases, and delays the end of the hydrogen-burning phase of the primary. Furthermore, it can change not only the occurrence of mass and angular momentum loss via the outer Lagrangian point, but also the contact or semi-contact status of the system. Thus, this effect can result in the special phenomenon of short-term variations occurring over a slow increase of the orbital period. The occurrence of mass and angular momentum loss via the outer Lagrangian point can affect the orbital period of the system significantly, but this process can be influenced, even suppressed out by the effect of rotation and tide. The mass and energy exchange occurs in the common envelope. The net result of the mass exchange process is a mass transfer from the primary to the secondary during the whole contact phase.展开更多
Type Ia supernovae(SNe Ia)play a key role in the fields of astrophysics and cosmology.It is widely accepted that SNe Ia arise from thermonuclear explosions of white dwarfs(WDs)in binary systems.However,there is no con...Type Ia supernovae(SNe Ia)play a key role in the fields of astrophysics and cosmology.It is widely accepted that SNe Ia arise from thermonuclear explosions of white dwarfs(WDs)in binary systems.However,there is no consensus on the fundamental aspects of the nature of SN Ia progenitors and their actual explosion mechanism.This fundamentally flaws our understanding of these important astrophysical objects.In this review,we outline the diversity of SNe Ia and the proposed progenitor models and explosion mechanisms.We discuss the recent theoretical and observational progress in addressing the SN Ia progenitor and explosion mechanism in terms of the observables at various stages of the explosion,including rates and delay times,pre-explosion companion stars,ejecta–companion interaction,early excess emission,early radio/X-ray emission from circumstellar material interaction,surviving companion stars,late-time spectra and photometry,polarization signals and supernova remnant properties.Despite the efforts from both the theoretical and observational sides,questions of how the WDs reach an explosive state and what progenitor systems are more likely to produce SNe Ia remain open.No single published model is able to consistently explain all observational features and the full diversity of SNe Ia.This may indicate that either a new progenitor paradigm or an improvement in current models is needed if all SNe Ia arise from the same origin.An alternative scenario is that different progenitor channels and explosion mechanisms contribute to SNe Ia.In the next decade,the ongoing campaigns with the James Webb Space Telescope,Gaia and the Zwicky Transient Facility,and upcoming extensive projects with the Vera C.Rubin Observatory's Legacy Survey of Space and Time and the Square Kilometre Array will allow us to conduct not only studies of individual SNe Ia in unprecedented detail but also systematic investigations for different subclasses of SNe Ia.This will advance theory and observations of SNe Ia sufficiently far to gain a deeper understanding of their origin and explosion mechanism.展开更多
The nature of the principle of equivalence is explored. The path of gravitons is analyzed in an accelerating system equivalent to a gravitating system. The finite speed of the graviton results in a delay of the gravit...The nature of the principle of equivalence is explored. The path of gravitons is analyzed in an accelerating system equivalent to a gravitating system. The finite speed of the graviton results in a delay of the gravitational interaction with a particle mass. From the aberration found in the path of the graviton we derive the standard expression for the advancement of the periastron of the orbit of the mass around a star. In a similar way, by analysing the aberrations of the graviton and light paths in an accelerating reference frame, the expression for the deflection of light by a massive body is obtained identically to the standard result. We also examine the binary star system and calculate the decay in its orbital period. The decay is attributed to the redshift of the graviton frequency relative to the accelerating system. Here too, we obtain good agreement with experimental measurements. Also, hypothesizing that gravitons behave like photons, we determine the temperature of the gravitons in a binary star system and form the Bose-Einstein distribution. Finally, we show how the redshift of gravitons may be the source of dark matter, dark energy and flat line spiral galaxy rotation curves.展开更多
A model for contact binary systems is presented, which incorporates the following special features： a） The energy exchange between the components is based on the understanding that the energy exchange is due to the ...A model for contact binary systems is presented, which incorporates the following special features： a） The energy exchange between the components is based on the understanding that the energy exchange is due to the release of potential, kinetic and thermal energies of the exchanged mass. b） A special form of mass and angular momentum loss occurring in contact binaries is losses via the outer Lagrangian point, c） The effects of spin, orbital rotation and tidal action on the stellar structure as well as the effect of meridian circulation on the mixing of the chemical elements are considered, d） The model is valid not only for low-mass contact binaries but also for high-mass contact binaries. For illustration, we used the model to trace the evolution of a massive binary system consisting of one 12M⊙ and one 5M⊙ star. The result shows that the start and end of the contact stage fall within the semi-detached phase during which the primary continually transfers mass to the secondary. The time span of the contact stage is short and the mass transfer rate is very large. Therefore, the contact stage can be regarded as a special part of the semi-detached phase with a large mass transfer rate. Both mass loss through the outer Lagrangian point and oscillation between contact and semi-contact states can occur during the contact phase, and the effective temperatures of the primary and the secondary are almost equal.展开更多
We present a comprehensive set of physical and geometrical parameters for each of the components of the close visual binary system HIP 11253(HD 14874).We present an analysis for the binary and multiple stellar systems...We present a comprehensive set of physical and geometrical parameters for each of the components of the close visual binary system HIP 11253(HD 14874).We present an analysis for the binary and multiple stellar systems with the aim to obtain a match between the overall observational spectral energy distribution of the system and the spectral synthesis created from model atmospheres using Al-Wardat's method for analyzing binary and multiple stellar systems.The epoch positions are used to determine the orbital parameters and the total mass.The parameters of both components are derived as:T_(eff)^(a)=6025,T_(eff)^(b)=4710,logg_(a)=4.55,logg_(b)=4.60,R_(a)=1.125 R_(⊙),R_(b)=0.88R_(⊙),L_(a)=1.849 L_(⊙),L_(b)=0.342 L_(⊙).Our analysis shows that the spectral types of the components are F9 and K3.By combining the orbital solution with the parallax measurements of Gaia DR2 and EDR3,we estimate the individual masses using the H-R diagram as M_(a)=1.09 M_(⊙)and M_(b)=0.59 M_(⊙)for using Gaia DR2 parallax and M_(a)=1.10 M_(⊙)and M_(b)=0.61 M_(⊙)for using Gaia EDR3 parallax.Finally,the location of both system's components on the stellar evolutionary tracks is presented.展开更多
In this paper,we present the analysis of the stellar system HIP 101227 to determine the actual number of components in the system,and their properties.We use dynamical modeling and complex spectrophotometric(involving...In this paper,we present the analysis of the stellar system HIP 101227 to determine the actual number of components in the system,and their properties.We use dynamical modeling and complex spectrophotometric(involving atmospheric modeling)techniques with recent data,to determine the physical properties and orbital solution for the system,respectively,with better accuracy than past studies.Based on our analysis,we found that the system is more consistent with being a quadruple rather than a binary or a triple system as suggested by previous studies.The total mass of the system determined from our SED analysis is 3.42±0.20 M,which is distributed almost equally between the four stars.The stars are found to be zero-age main sequence stars;i.e.,at the last stage of pre-main sequence,with age less than 200 Myr and spectral types K0.All four stars have very similar physical characteristics,suggesting that the fragmentation process is the most likely theory for the formation and evolution of the system.展开更多
The first photometric light curve investigation of the NSVS 8294044,V1023 Her,and V1397 Her binary systems is presented.We used ground-based observations for the NSVS 8294044 system and Transiting Exoplanet Survey Sat...The first photometric light curve investigation of the NSVS 8294044,V1023 Her,and V1397 Her binary systems is presented.We used ground-based observations for the NSVS 8294044 system and Transiting Exoplanet Survey Satellite data for V1023 Her and V1397 Her.The primary and secondary times of minima were extracted from al the data,and,by collecting the literature,a new ephemeris was computed for each system.Linear fits for the O-C diagrams were conducted using the Markov Chain Monte Carlo (MCMC) method.Light curve solutions were performed using the PHysics Of Eclipsing BinariEs Python code and the MCMC approach.The systems were found to be contact binary stars based on the fillout factor and mass ratio.V1023 Her showed the O’Connell effect and a cold starspot on the secondary component was required for the light curve solution.The absolute parameters of the system were estimated based on an empirical relationship between orbital period and mass.We presented a new T–M equation based on a sample of 428 contact binary systems and found that our three target systems were in good agreement with the fit.The positions of the systems were also depicted on the M–L,M–R,q–L_(ratio),and M_(tot)–J_(0)diagrams in the logarithmic scales.展开更多
The study reports photometric and spectroscopic observations of two recently recognized contact binary systems.Both systems show total eclipses and analysis of the light curves indicates both have very low mass ratios...The study reports photometric and spectroscopic observations of two recently recognized contact binary systems.Both systems show total eclipses and analysis of the light curves indicates both have very low mass ratios of less than 0.3.We derive absolute parameters from color and distance based calibrations and show that,although both have low mass ratios,they are likely to be in a stable orbit and unlikely to merge.In other respects,both systems have characteristics similar to other contact binaries with the secondary larger and brighter than their main sequence counterparts and we also find that the secondary is considerably denser than the primary in both systems.展开更多
We present the detailed fundamental stellar parameters of the close visual binary system HD 39438 for the first time. We used Al-Wardat's method for analyzing binary and multiple stellar systems. The method implem...We present the detailed fundamental stellar parameters of the close visual binary system HD 39438 for the first time. We used Al-Wardat's method for analyzing binary and multiple stellar systems. The method implements Kurucz's plane parallel model atmospheres to construct synthetic spectral energy distributions(SEDs) for both components of the system. It then combines the results of the spectroscopic analysis with the photometric analysis and compares them with the observed ones to construct the best synthetic SED for the combined system. The analysis gives the precise fundamental parameters of the individual components of the system. Based on the positions of the components of HD 39438 on the H-R diagram, and evolutionary and isochrone tracks, we found that the system belongs to the main sequence stars with masses of 1.24 and 0.98 solar masses for the components A and B, respectively, and age of 1.995 Gyr for both components. The main result of HD 39438 is new dynamical parallax, which is estimated to be 16.689 ± 0.03 mas.展开更多
A photometric study of a contact binary system, GV Leo is presented. New observations were done using the B VR filter bands. We find that a revised orbital period is 0.26673171 d and the orbital period of this system ...A photometric study of a contact binary system, GV Leo is presented. New observations were done using the B VR filter bands. We find that a revised orbital period is 0.26673171 d and the orbital period of this system is decreasing at a rate of dP/ dt = -4.95 × 10-7 d yr-1. The photometric solutions are fairly well fitted at a mass ratio of q = 0.1879, with a fillout factor of f = 17.74%. The results indicate that there exists mass transfer from the more massive component to the less massive one at a rate of relative mass exchange, 6zl/m = -1.09× 10-7 yr-1. It is possible that this weak- contact system, that shows a decreasing orbital period, may undergo contraction of the inner and outer critical Roche lobes and evolve into a deep-contact binary.展开更多
基金a project supported by the Scientific and Technological Research Council of Türkiye (TüB?TAK) under grant No.114F166
文摘We present a comprehensive analysis of BI CVn,an eclipsing overcontact binary system.New BVR photometric observations,combined with available spectroscopic data,were analyzed simultaneously using the Wilson–Devinney method to derive the orbital and physical parameters of the system.The resulting stellar parameters are M1=0.58±0.01M⊙,M2=1.42±0.02M⊙,R1=0.88±0.01R⊙,R2=1.31±0.01R⊙,with an orbital separation of a=2.80±0.01R⊙.Based on all available CCD times of minimum light,including both ground-based and T ESS observations,the(O-C)diagram of BI CVn was analyzed.T he orbital period exhibits a long-term decrease at a rate of-2.3239(±0.0001)×10-8 day yr-1,likely due to mass transfer from the more massive to the less massive component.Superimposed on this trend is a cyclic variation with a period of 56.84±0.08 yr,indicative of a light-travel time effect caused by a third body,whose estimated mass is 0.63±0.02M⊙.Using these derived parameters,we modeled the binary’s evolution through non-conservative processes with the Binary Star Evolution code.The evolutionary tracks of the components were examined in multiple parameter planes,leading to an estimated merger timescale of approximately 2.70 Gyr.
文摘The action of gravitons in a binary star system is modelled as the locus of points on an ellipse synchronous to the elliptic orbit of the binary star. In their interaction between the masses in the system the rotational energy of the gravitons is reduced by gravitational redshift, which accounts for the decay of the binary star orbital period. This model is able to fit a broad range of eccentricities of binary pulsar orbits and orbital period decay comparable to the General Relativistic gravitational wave model.
基金supported by the National Key R&D Program of China for the Intergovernmental Scientific and Technological Innovation Cooperation Project under No.2022YFE0126200Tianshan Talent Training Program under No.2023TSYCLJ0053+3 种基金supported by the National Natural Science Foundation of China under grant Nos.12090040/4,12022304,11973052,11973042,U1931102,12373036the National Key R&D Program of China No.2019YFA0405502support from the Guo Shou Jing TelescopeGuo Shou Jing Telescope(the Large Sky Area Multi-Object Fiber Spectroscopic Telescope LAMOST)is a National Major Scientific Project built by the Chinese Academy of Sciences.Funding for the project has been provided by the National Development and Reform Commission.
文摘We present a detailed analysis of a double-lined spectroscopic binary system,Bo Gem,using data obtained from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)and the Transiting Exoplanet Survey Satellite(TESS).By applying spectral disentangling techniques to the LAMOST Medium Resolution Spectra,we determine the orbital parameters,including the orbital period of P=4.0689 days,and semimajor axis of a=14.90±0.04 R_(⊙).The mass ratio between the two components is found to be q=0.198±0.006,with an inclination of i=82°.3±0°.13.The photometric data from TESS revealed periodic light variations due to the eclipsing nature of the system,allowing for the determination of the primary star’s radius as R_(1)=1.68±0.03 R_(⊙)and the secondary star’s radius as R_(2)=3.68±0.04 R_(⊙).The effective temperatures of the primary and secondary stars are measured to be T_(eff,1)=9705±50 K and T_(eff,2)=5830±22 K,respectively.By analyzing the disentangled spectra,we determined the stellar atmospheric parameters—including surface gravity and metallicity of both stars.These results not only confirm the double-lined spectroscopic binary status of Bo Gem,but also underscore its value as an important system for testing and refining stellar evolution models.
文摘Al-Wardat's method is used in this research to analyze the two components of the HD 25811 binary system,which combines the results of speckle interferometry with the astrometric data to construct the synthetic spectral energy distribution of the system.The method results in the effective temperatures at 7100±50 K for component A and 7000±50 K for component B,while their masses measure as 1.65±0.15M_(⊙)for component A and1.58±0.14M_(⊙)for component B.The system exists at an estimated age of 0.794 Gyr,while both stars remain in their initial subgiant evolutionary phase.The evolutionary tracks together with isochrones for Z=0.03 validate that the system components share both their origin and chemical compositions.The orbital analysis shows that the system has a period of 15.97 yr and an eccentricity of 0.713,while the total system mass amounts to3.65±0.49 M_(⊙).We detailedly analyze the system's orbital dynamics to assess planetary stability and habitability zones,which lead to the dynamics of circumbinary(P-type)and circumstellar(S-type)orbits using empirical criteria,revealing large regions in which planetary orbits remain dynamically stable.Luminosities and effective temperatures of each stellar component are used to determine their habitable zones.
基金support of the Russian Foundation for Basic Research under Contract No.20-02-00563A.
文摘Based on positional observations and measurements of radial velocities,the orbits of 850 wide visual binary stars have been determined.The parameters of the log-normal distributions for the histograms of orbital periods,stellar masses,and semimajor axes in astronomical units have been obtained.The eccentricity histogram for binary stars with orbital periods less than 400 yr follows a normal distribution centered at e=0.545+/−0.029.For stars with longer periods,this distribution obeys the law f=2e,with accuracy to errors.The mass-to-luminosity relation for stars with well-determined masses is given by:log L_(⊙)=4.33 logM_(⊙)-0.11,where L_(⊙) and M_(⊙) are the luminosity and mass of the star in units of the solar luminosity and mass,respectively.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDB0550400)the National Key Research and Development Program of China(Nos.2024YFA1611704 and 2021YFA0718500)the National Natural Science Foundation of China(NSFC,Nos.12473049,12041301,12121003,and 12225305).
文摘Most massive stars reside in binary or multi-object systems.Short gamma-ray bursts(sGRBs),the product of the merger of double compact objects,may originate from massive common-envelope binaries.In contrast,the progenitors of long GRBs(lGRBs)are typically considered isolated massive stars.However,no effective method has yet been established to identify potential companions from current observations.Recent studies have demonstrated that quasi-periodic oscillation signatures can serve as a promising tool to probe the properties of GRB central engines.In this study,by drawing an analogy to periodicity in X-ray binaries,we explore the precession periods of companion-induced disk precession for lGRBs born in the ultra-compact binary scenario.Our results suggest that the periodicity observed in lGRB afterglows,measured in units of 1000 s or more,may indicate that lGRBs originate within binary systems.GRB 050904 could represent a rare case where the burst occurred in a binary system,leaving behind a black hole–black hole binary at redshift z=6.29.
文摘AR Aur A+B is a close binary of astrophysical interest because dissimilar surface compositions are reported between similar late B-type dwarfs.A new spectroscopic study on this system was carried out based on the disentangled spectra,in order to determine their atmospheric parameters and elemental abundances.The effective temperature and microturbulence(determined from the equivalent widths of Fe II lines)turned out to be(11,150 K,0.9 km s^(-1))and(10,650 K,0.1 km s^(-1))for A and B,respectively.The chemical abundances of 28 elements were then derived while taking into account the non-LTE effect for Z≤15 elements(Z:atomic number).The following trends were elucidated for[X/H](abundance of X relative to the Sun):(1)Qualitatively,[X/H]shows a rough global tendency to increase with Z,with the gradient steeper for A than for B.(2)However,considerable dispersion is involved for A,since prominently large peculiarities are seen in specific elements reflecting the characteristics of HgMn stars(e.g.,very deficient N,Al,Sc,Ni;markedly overabundant P,Mn).(3)In contrast,the Z-dependence of[X/H]for B tends to be nearly linear with only a small dispersion.These observational facts may serve as a key to understanding the critical condition for the emergence of the chemical anomaly.
基金supported by the Ministry of Science and Education,FEUZ-2020-0030。
文摘We investigate the exchange of mass in a binary system as a channel through which a Be star can receive a rapid rotation.The mass-transfer phase in a massive close binary system in the Hertzsprung-gap is accompanied by the spinning up of the accreting component.We consider a case when the mass of the accreting component increases by 1.5 times.The component acquires mass and angular momentum while in a state of critical rotation.The angular momentum of the component increases by 50 times.Meridional circulation effectively transports angular momentum inside the component during the mass-transfer phase and during the thermal timescale after the end of the mass-transfer phase.As a result of mass transfer,the component acquires the rotation typical of classical Be stars.
基金supported by the Ministry of Science and EducationFEUZ-2023-0019。
文摘This paper investigates the spin-up of a mass-accreting star in a close binary system passing through the first stage of mass exchange in the Hertzsprung gap. Inside an accreting star, angular momentum is carried by meridional circulation and shear turbulence. The circulation carries part of the angular momentum of the accreted layers to the accretor's surface. The greater the rate of arrival of angular momentum in the accretor is, the greater this part. It is assumed that this part of the angular momentum can be removed by the disk further from the accretor. If the angular momentum in the matter entering the accretor is more than half the Keplerian value, then the angular momentum obtained by the accretor during mass exchange stage does not depend on the rate of arrival of angular momentum. The accretor may have the characteristics of a Be-star immediately after the end of mass exchange.
基金the Scientific and Technological Research Council(TUBITAK)under Grant No.120F330Funding for the TESS mission is provided by the NASA Explorer Program。
文摘The existence of pulsating stars in eclipsing binaries has been known for decades.These types of objects are extremely valuable systems for astronomical studies as they exhibit both eclipse and pulsation variations.The eclipsing binaries are the only way to directly measure the mass and radius of stars with a good accuracy(≤1%),while the pulsations are a unique way to probe the stellar interior via oscillation frequencies.There are different types of pulsating stars existing in eclipsing binaries.One of them is theδScuti variables.Currently,the known number ofδScuti stars in eclipsing binaries is around 90 according to the latest catalog of these variables.An increasing number of these kinds of variables is important to understand the stellar structure,evolution and the effect of binarity on the pulsations.Therefore,in this study,we focus on discovering new eclipsing binaries withδScuti component(s).We searched within the northern Transiting Exoplanet Survey Satellite(TESS)field with a visual inspection by following some criteria such as light curve shape,the existence of pulsation like variations in the out-of-eclipse light curve and the T_(eff) values of the targets.As a result of these criteria,we discovered some targets.The orbital variations were first removed from the TESS light curves and frequency analysis was performed on the residuals.The luminosity,and absolute and bolometric magnitudes of the targets were calculated as well.To find how much of these parameters represent the primary(more luminous)binary component,we also computed the flux density ratio of the systems by utilizing the area of the eclipses.In addition,the positions of the systems in the H-R diagram were examined considering the flux density ratios.As a consequence of the investigation,we defined 38 candidateδScuti stars and also one Maia variable in eclipsing binary systems.
基金Supported by the National Natural Science Foundation of China.
文摘Three important physical processes occurring in contact binary systems are studied. The first one is the effect of spin, orbital rotation and tide on the structure of the components, which includes also the effect of meridian circulation on the mixing of the chemical elements in the components. The second one is the mass and energy exchange between the components. To describe the energy exchange, a new approach is introduced based on the understanding that the exchange is due to the release of the potential, kinetic and thermal energy of the exchanged mass. The third is the loss of mass and angular momentum through the outer Lagrangian point. The rate of mass loss and the angular momentum carded away by the lost mass are discussed. To show the effects of these processes, we follow the evolution of a binary system consisting of a 12M⊙ and a 5M⊙ star with mass exchange between the components and mass loss via the outer Lagrangian point, both with and without considering the effects of rotation and tide. The result shows that the effect of rotation and tide advances the start of the semi-detached and the contact phases, and delays the end of the hydrogen-burning phase of the primary. Furthermore, it can change not only the occurrence of mass and angular momentum loss via the outer Lagrangian point, but also the contact or semi-contact status of the system. Thus, this effect can result in the special phenomenon of short-term variations occurring over a slow increase of the orbital period. The occurrence of mass and angular momentum loss via the outer Lagrangian point can affect the orbital period of the system significantly, but this process can be influenced, even suppressed out by the effect of rotation and tide. The mass and energy exchange occurs in the common envelope. The net result of the mass exchange process is a mass transfer from the primary to the secondary during the whole contact phase.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.12288102,12090040/1,11873016)the National Key R&D Program of China(Nos.2021YFA1600401 and 2021YFA1600400)+4 种基金the Chinese Academy of Sciences(CAS),the International Centre of Supernovae,Yunnan Key Laboratory(No.202302AN360001)the Yunnan Fundamental Research Projects(grant Nos.202201BC070003,202001AW070007)the“Yunnan Revitalization Talent Support Program”Science&Technology Champion Project(No.202305AB350003)supported by the Klaus Tschira Foundationby the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)—Project-ID 138713538—SFB 881(“The Milky Way System”,Subproject A10)。
文摘Type Ia supernovae(SNe Ia)play a key role in the fields of astrophysics and cosmology.It is widely accepted that SNe Ia arise from thermonuclear explosions of white dwarfs(WDs)in binary systems.However,there is no consensus on the fundamental aspects of the nature of SN Ia progenitors and their actual explosion mechanism.This fundamentally flaws our understanding of these important astrophysical objects.In this review,we outline the diversity of SNe Ia and the proposed progenitor models and explosion mechanisms.We discuss the recent theoretical and observational progress in addressing the SN Ia progenitor and explosion mechanism in terms of the observables at various stages of the explosion,including rates and delay times,pre-explosion companion stars,ejecta–companion interaction,early excess emission,early radio/X-ray emission from circumstellar material interaction,surviving companion stars,late-time spectra and photometry,polarization signals and supernova remnant properties.Despite the efforts from both the theoretical and observational sides,questions of how the WDs reach an explosive state and what progenitor systems are more likely to produce SNe Ia remain open.No single published model is able to consistently explain all observational features and the full diversity of SNe Ia.This may indicate that either a new progenitor paradigm or an improvement in current models is needed if all SNe Ia arise from the same origin.An alternative scenario is that different progenitor channels and explosion mechanisms contribute to SNe Ia.In the next decade,the ongoing campaigns with the James Webb Space Telescope,Gaia and the Zwicky Transient Facility,and upcoming extensive projects with the Vera C.Rubin Observatory's Legacy Survey of Space and Time and the Square Kilometre Array will allow us to conduct not only studies of individual SNe Ia in unprecedented detail but also systematic investigations for different subclasses of SNe Ia.This will advance theory and observations of SNe Ia sufficiently far to gain a deeper understanding of their origin and explosion mechanism.
文摘The nature of the principle of equivalence is explored. The path of gravitons is analyzed in an accelerating system equivalent to a gravitating system. The finite speed of the graviton results in a delay of the gravitational interaction with a particle mass. From the aberration found in the path of the graviton we derive the standard expression for the advancement of the periastron of the orbit of the mass around a star. In a similar way, by analysing the aberrations of the graviton and light paths in an accelerating reference frame, the expression for the deflection of light by a massive body is obtained identically to the standard result. We also examine the binary star system and calculate the decay in its orbital period. The decay is attributed to the redshift of the graviton frequency relative to the accelerating system. Here too, we obtain good agreement with experimental measurements. Also, hypothesizing that gravitons behave like photons, we determine the temperature of the gravitons in a binary star system and form the Bose-Einstein distribution. Finally, we show how the redshift of gravitons may be the source of dark matter, dark energy and flat line spiral galaxy rotation curves.
基金the National Natural Science Foundation of China.
文摘A model for contact binary systems is presented, which incorporates the following special features： a） The energy exchange between the components is based on the understanding that the energy exchange is due to the release of potential, kinetic and thermal energies of the exchanged mass. b） A special form of mass and angular momentum loss occurring in contact binaries is losses via the outer Lagrangian point, c） The effects of spin, orbital rotation and tidal action on the stellar structure as well as the effect of meridian circulation on the mixing of the chemical elements are considered, d） The model is valid not only for low-mass contact binaries but also for high-mass contact binaries. For illustration, we used the model to trace the evolution of a massive binary system consisting of one 12M⊙ and one 5M⊙ star. The result shows that the start and end of the contact stage fall within the semi-detached phase during which the primary continually transfers mass to the secondary. The time span of the contact stage is short and the mass transfer rate is very large. Therefore, the contact stage can be regarded as a special part of the semi-detached phase with a large mass transfer rate. Both mass loss through the outer Lagrangian point and oscillation between contact and semi-contact states can occur during the contact phase, and the effective temperatures of the primary and the secondary are almost equal.
文摘We present a comprehensive set of physical and geometrical parameters for each of the components of the close visual binary system HIP 11253(HD 14874).We present an analysis for the binary and multiple stellar systems with the aim to obtain a match between the overall observational spectral energy distribution of the system and the spectral synthesis created from model atmospheres using Al-Wardat's method for analyzing binary and multiple stellar systems.The epoch positions are used to determine the orbital parameters and the total mass.The parameters of both components are derived as:T_(eff)^(a)=6025,T_(eff)^(b)=4710,logg_(a)=4.55,logg_(b)=4.60,R_(a)=1.125 R_(⊙),R_(b)=0.88R_(⊙),L_(a)=1.849 L_(⊙),L_(b)=0.342 L_(⊙).Our analysis shows that the spectral types of the components are F9 and K3.By combining the orbital solution with the parallax measurements of Gaia DR2 and EDR3,we estimate the individual masses using the H-R diagram as M_(a)=1.09 M_(⊙)and M_(b)=0.59 M_(⊙)for using Gaia DR2 parallax and M_(a)=1.10 M_(⊙)and M_(b)=0.61 M_(⊙)for using Gaia EDR3 parallax.Finally,the location of both system's components on the stellar evolutionary tracks is presented.
基金A.Annuar acknowledges financial support from Malaysia’s Ministry of Higher Education Fundamental Research Grant Scheme code FRGS/1/2019/STG02/UKM/02/7This work has made use of the SAO/NASA,SIMBAD database,Fourth Catalog of Interferometric Measurements of Binary Stars,Sixth Catalog of Orbits of Visual Binary Stars,IPAC data systems,ORBITX code and Al-Wardat’s complex method for analyzing CVBMSs with its codes,written in FORTRAN and Interactive Data Language(IDL)of the ITT Visual Information Solutions Corporation.
文摘In this paper,we present the analysis of the stellar system HIP 101227 to determine the actual number of components in the system,and their properties.We use dynamical modeling and complex spectrophotometric(involving atmospheric modeling)techniques with recent data,to determine the physical properties and orbital solution for the system,respectively,with better accuracy than past studies.Based on our analysis,we found that the system is more consistent with being a quadruple rather than a binary or a triple system as suggested by previous studies.The total mass of the system determined from our SED analysis is 3.42±0.20 M,which is distributed almost equally between the four stars.The stars are found to be zero-age main sequence stars;i.e.,at the last stage of pre-main sequence,with age less than 200 Myr and spectral types K0.All four stars have very similar physical characteristics,suggesting that the fragmentation process is the most likely theory for the formation and evolution of the system.
文摘The first photometric light curve investigation of the NSVS 8294044,V1023 Her,and V1397 Her binary systems is presented.We used ground-based observations for the NSVS 8294044 system and Transiting Exoplanet Survey Satellite data for V1023 Her and V1397 Her.The primary and secondary times of minima were extracted from al the data,and,by collecting the literature,a new ephemeris was computed for each system.Linear fits for the O-C diagrams were conducted using the Markov Chain Monte Carlo (MCMC) method.Light curve solutions were performed using the PHysics Of Eclipsing BinariEs Python code and the MCMC approach.The systems were found to be contact binary stars based on the fillout factor and mass ratio.V1023 Her showed the O’Connell effect and a cold starspot on the secondary component was required for the light curve solution.The absolute parameters of the system were estimated based on an empirical relationship between orbital period and mass.We presented a new T–M equation based on a sample of 428 contact binary systems and found that our three target systems were in good agreement with the fit.The positions of the systems were also depicted on the M–L,M–R,q–L_(ratio),and M_(tot)–J_(0)diagrams in the logarithmic scales.
基金funded by MCIN/AEI/10.13039/501100011033/through grant PID2020-112949GB-100partially updated by using funding from the European Union's Horizon2020 Research and Innovation Programme,under grant Agreement No.776403(EXOPLANETS-A)financial support of the Ministry of Education,Science and Technological Development of the Republic of Serbia through contract No.451-03-9/2021-14/200002。
文摘The study reports photometric and spectroscopic observations of two recently recognized contact binary systems.Both systems show total eclipses and analysis of the light curves indicates both have very low mass ratios of less than 0.3.We derive absolute parameters from color and distance based calibrations and show that,although both have low mass ratios,they are likely to be in a stable orbit and unlikely to merge.In other respects,both systems have characteristics similar to other contact binaries with the secondary larger and brighter than their main sequence counterparts and we also find that the secondary is considerably denser than the primary in both systems.
文摘We present the detailed fundamental stellar parameters of the close visual binary system HD 39438 for the first time. We used Al-Wardat's method for analyzing binary and multiple stellar systems. The method implements Kurucz's plane parallel model atmospheres to construct synthetic spectral energy distributions(SEDs) for both components of the system. It then combines the results of the spectroscopic analysis with the photometric analysis and compares them with the observed ones to construct the best synthetic SED for the combined system. The analysis gives the precise fundamental parameters of the individual components of the system. Based on the positions of the components of HD 39438 on the H-R diagram, and evolutionary and isochrone tracks, we found that the system belongs to the main sequence stars with masses of 1.24 and 0.98 solar masses for the components A and B, respectively, and age of 1.995 Gyr for both components. The main result of HD 39438 is new dynamical parallax, which is estimated to be 16.689 ± 0.03 mas.
基金support by the Faculty of Science,Chiang Mai University
文摘A photometric study of a contact binary system, GV Leo is presented. New observations were done using the B VR filter bands. We find that a revised orbital period is 0.26673171 d and the orbital period of this system is decreasing at a rate of dP/ dt = -4.95 × 10-7 d yr-1. The photometric solutions are fairly well fitted at a mass ratio of q = 0.1879, with a fillout factor of f = 17.74%. The results indicate that there exists mass transfer from the more massive component to the less massive one at a rate of relative mass exchange, 6zl/m = -1.09× 10-7 yr-1. It is possible that this weak- contact system, that shows a decreasing orbital period, may undergo contraction of the inner and outer critical Roche lobes and evolve into a deep-contact binary.
