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The W UMa binaries USNO-A2.0 1350-17365531,V471 Cas,V479 Lac and V560 Lac:light curve solutions and global parameters based on Gaia distances 被引量:2
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作者 Diana P.Kjurkchieva Velimir A.Popov +1 位作者 Yordanka Eneva Nikola I.Petrov 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2019年第1期141-148,共8页
We present photometric observations in Sloan filters g′, i′of the eclipsing W UMa stars USNOA2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac. The sinusoidal-like O-C diagram of V471 Cas indicates the presence of ... We present photometric observations in Sloan filters g′, i′of the eclipsing W UMa stars USNOA2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac. The sinusoidal-like O-C diagram of V471 Cas indicates the presence of a third body with mass 0.12 M_⊙(a red dwarf) at distance 897 R_⊙. The O-C diagram of V479 Lac reveals a period decrease of d P/dt =-1.69 × 10-6d yr-1. The results of the light curve solutions are:(i) the targets are overcontact binaries with small fill-out factors;(ii) their components are F–K stars, comparable in size, whose temperature differences are below 80 K;(iii) all targets undergo partial eclipses and to limit the possible mass ratios we carried out two-step q-search analysis. The target global parameters(luminosities, radii, masses) were obtained on the basis of their Gaia distances and the results of our light curve solutions. The obtained total mass of V560 Lac turns out to be smaller than the lower mass limit for presently known W UMa binaries of 1.0-1.2 M_⊙, i.e. this target is a peculiar overcontact system. 展开更多
关键词 binaries:close binaries:eclipsing methods:data analysis stars:fundamental PARAMETERS stars:individual(USNO-A2.0 1350-17365531 V471 Cas V479 Lac V560 Lac)
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Study of 26 Galactic Open Clusters with Extended Main-sequence Turnoffs
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作者 Yang-Yang Deng Zhong-Mu Li 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第6期28-37,共10页
Recent studies indicate that some Galactic open clusters(OCs)exhibit extended main-sequence turnoff(eMSTO)in their color–magnitude diagrams(CMDs).However,the number of Galactic OCs with eMSTO structures detected so f... Recent studies indicate that some Galactic open clusters(OCs)exhibit extended main-sequence turnoff(eMSTO)in their color–magnitude diagrams(CMDs).However,the number of Galactic OCs with eMSTO structures detected so far is limited,and the reasons for their formation are still unclear.This work identifies 26 Galactic OCs with undiscovered eMSTOs and investigates the causes of these features.Stellar population types and fundamental parameters of cluster samples are acquired using CMD fitting methods.Among them,the results of 11 OCs are reliable as the observed CMDs are well-reproduced.We propose the crucial role of stellar binarity and confirm the importance of stellar rotation in reproducing eMSTO morphologies.The results also show that the impact of age spread is important,as it can adequately explain the structure of young OCs and fit the observed CMDs of intermediate-age OCs better. 展开更多
关键词 (stars:)binaries:general Galaxy:fundamental parameters (Galaxy:)open clusters and associations:general (stars:)Hertzsprung Russell and C-M-diagrams
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Point-symmetry in SNR G1.9+0.3:A Supernova that Destroyed its Planetary Nebula Progenitor
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作者 Noam Soker 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第1期165-172,共8页
I analyze a new X-ray image of the youngest supernova remnant(SNR)in the Galaxy,which is the type Ia SNR G1.9+0.3,and reveal a very clear point-symmetrical structure.Since explosion models of type Ia supernovae(SNe Ia... I analyze a new X-ray image of the youngest supernova remnant(SNR)in the Galaxy,which is the type Ia SNR G1.9+0.3,and reveal a very clear point-symmetrical structure.Since explosion models of type Ia supernovae(SNe Ia)do not form such morphologies,the point-symmetrical morphology must come from the circumstellar material(CSM)into which the ejecta expands.The large-scale point-symmetry that I identify and the known substantial deceleration of the ejecta of SNR G1.9+0.3 suggest a relatively massive CSM of■1M⊙.I argue that the most likely explanation is the explosion of this SN Ia into a planetary nebula.The scenario that predicts a large fraction of SN Ia inside PNe(SNIPs)is the core degenerate scenario.Other SN Ia scenarios might lead to only a very small fraction of SNIPs or none at all. 展开更多
关键词 (stars:)supernovae:general ISM:supernova remnants (stars:)binaries(including multiple):close (ISM:)planetary nebulae:general stars:jets
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Investigations into the thermal non-equilibrium of W UMa-type contact binaries
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作者 Xiao Xiong Liang Liu Sheng-Bang Qian 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2018年第5期83-92,共10页
Traditionally, some physical details(e.g., magnetic braking, energy transfer, angular momentum loss, etc.) have to be taken into consideration during investigations into the evolution of contact binaries. However, t... Traditionally, some physical details(e.g., magnetic braking, energy transfer, angular momentum loss, etc.) have to be taken into consideration during investigations into the evolution of contact binaries. However, the real evolutionary processes which usually contain several of these physical mechanisms are very complicated as a result of strong interaction between components. To avoid dealing with these factors, a linear relationship is applied to the temperatures of components. It is found that the higher the mass ratio(M2/M1) of a contact system, the weaker the deviation from thermal equilibrium.On this basis, a variation trend of fill-out factor(f) changing with mass ratio can be inferred, which is consistent with observations. Moreover, if we stick to this point of view, it should be natural that the number of semi-detached binaries in the predicted broken-contact phase of relaxation oscillations is less than the number in the contact phase. 展开更多
关键词 STARS binaries close - stars binaries eclipsing - stars evolution
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The formation of neutron star systems through accretion-induced collapse in white-dwarf binaries
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作者 Bo Wang Dongdong Liu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2020年第9期135-158,共24页
The accretion-induced collapse(AIC)scenario was proposed 40 years ago as an evolutionary end state of oxygen-neon white dwarfs(ONe WDs),linking them to the formation of neutron star(NS)systems.However,there has been n... The accretion-induced collapse(AIC)scenario was proposed 40 years ago as an evolutionary end state of oxygen-neon white dwarfs(ONe WDs),linking them to the formation of neutron star(NS)systems.However,there has been no direct detection of any AIC event so far,even though there exists a lot of indirect observational evidence.Meanwhile,the evolutionary pathways resulting in NS formation through AIC are still not thoroughly investigated.In this article,we review recent studies on the two classic progenitor models of AIC events,i.e.,the single-degenerate model(including the ONe WD+MS/RG/He star channels and the CO WD+He star channel)and the double-degenerate model(including the double CO WD channel,the double ONe WD channel and the ONe WD+CO WD channel).Recent progress on these progenitor models is reviewed,including the evolutionary scenarios leading to AIC events,the initial parameter space for producing AIC events and the related objects(e.g.,the pre-AIC systems and the post-AIC systems).For the single-degenerate model,the pre-AIC systems(i.e.,the progenitor systems of AIC events)could potentially be identified as supersoft X-ray sources,symbiotics and cataclysmic variables(such as classical novae,recurrent novae,Ne novae and He novae)in the observations,whereas the post-AIC systems(i.e.,NS systems)could potentially be identified as low-/intermediate-mass X-ray binaries,and the resulting low-/intermediate-mass binary pulsars,most notably millisecond pulsars.For the double-degenerate model,the pre-AIC systems are close double WDs with short orbital periods,whereas the post-AIC systems are single isolated NSs that may correspond to a specific kind of NS with peculiar properties.We also review the predicted rates of AIC events,the mass distribution of NSs produced via AIC and the gravitational wave(GW)signals from double WDs that are potential GW sources in the Galaxy in the context of future spacebased GW detectors,such as LISA,TianQin,Taiji,etc.Recent theoretical and observational constraints on the detection of AIC events are summarized.In order to confirm the existence of the AIC process,and resolve this long-term issue presented by current stellar evolution theories,more numerical simulations and observational identifications are required. 展开更多
关键词 binaries:close white dwarfs supernovae:general stars:neutron stars:evolution
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Searching forγ-ray counterparts to very faint X-ray transient neutron star binaries
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作者 Ge-Ge Wang Zhong-Xiang Wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2018年第9期47-52,共6页
Very faint X-ray transients (VFXTs) are a group of X-ray binaries with low luminosities, displaying peak X-ray luminosities during their outbursts of only 1034-1036 erg s^-1. Using γ-ray data obtained with the Larg... Very faint X-ray transients (VFXTs) are a group of X-ray binaries with low luminosities, displaying peak X-ray luminosities during their outbursts of only 1034-1036 erg s^-1. Using γ-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope (Fermi), we investigate their possible nature of containing rotation-powered pulsars, or more specifically being transitional millisecond pulsars (MSPs). Among more than 40 known VFXTs, we select 12 neutron star systems. We analyze the LAT data for the fields of 12 VFXTs in the energy range 0.2-300GeV, but do not find any counterparts likely detected by Fermi. We obtain luminosity upper limits for the 12 sources. While the distances to the sources are largely uncertain, the upper limits are comparable to the luminosities of two transitional systems, PSR J1023-0038 and XSS J12270-4859. From our study, we conclude that no evidence is found at γ-rays for the suggestion that some VFXTs could contain rotation-powered MSPs (or be transitional MSP systems). 展开更多
关键词 STARS pulsars - stars binaries - gamma rays STARS
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Quark-novae in neutron star - white dwarf binaries: a model for luminous (spin-down powered) sub-Chandrasekhar-mass Type Ia supernovae?
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作者 Rachid Ouyed Jan Staff 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2013年第4期435-464,共30页
We show that, by appealing to a Quark-Nova (QN) in a tight binary system containing a massive neutron star and a CO white dwarf (WD), a Type Ia explosion could occur. The QN ejecta collides with the WD, driving a ... We show that, by appealing to a Quark-Nova (QN) in a tight binary system containing a massive neutron star and a CO white dwarf (WD), a Type Ia explosion could occur. The QN ejecta collides with the WD, driving a shock that triggers carbon burning under degenerate conditions (the QN-Ia). The conditions in the compressed low-mass WD (MwD 〈 0.9 M) in our model mimic those of a Chandrasekhar mass WD. The spin-down luminosity from the QN compact remnant (the quark star) pro- vides additional power that makes the QN-Ia light-curve brighter and broader than a standard SN-Ia with similar 56Ni yield. In QNe-Ia, photometry and spectroscopy are not necessarily linked since the kinetic energy of the ejecta has a contribution from spin-down power and nuclear decay. Although QNe-Ia may not obey the Phillips relationship, their brightness and their relatively "normal looking" light-curves mean they could be included in the cosmological sample. Light-curve fitters would be con- fused by the discrepancy between spectroscopy at peak and photometry and would correct for it by effectively brightening or dimming the QNe-Ia apparent magnitudes, thus over- or under-estimating the true magnitude of these spin-down powered SNe-Ia. Contamination of QNe-Ia in samples of SNe-Ia used for cosmological analyses could systematically bias measurements of cosmological parameters if QNe-Ia are numerous enough at high-redshift. The strong mixing induced by spin-down wind combined with the low 56Ni yields in QNe-Ia means that these would lack a secondary maximum in the/-band despite their luminous nature. We discuss possible QNe-Ia progenitors. 展开更多
关键词 stars evolution - stars binary - stars neutron - stars white dwarfs - supernovae general
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On pulsar-driven mass ejection in low-mass X-ray binaries
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作者 Lei Fu Xiang-Dong Li 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2011年第12期1457-1468,共12页
There is accumulating evidence for mass ejection in low-mass X-ray binaries (LMXBs) driven by radio pulsar activity during X-ray quiescence. We consider the condition for mass ejection by comparing the radiation pre... There is accumulating evidence for mass ejection in low-mass X-ray binaries (LMXBs) driven by radio pulsar activity during X-ray quiescence. We consider the condition for mass ejection by comparing the radiation pressure from a millisecond pulsar, and the gas pressure at the inner Lagrange point or at the surrounding accretion disk. We calculate the critical spin period of the pulsar below which mass ejection is allowed. Combining with the evolution of the mass transfer rate, we present constraints on the orbital periods of the systems. We show that mass ejection could happen in both wide and compact LMXBs. It may be caused by transient accretion due to thermal instability in the accretion disks in the former, and irradiation-driven mass-transfer cycles in the latter. 展开更多
关键词 pulsars: general- binaries general
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Two particular EA-type binaries in the globular cluster ω Centauri
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作者 Kai Li Sheng-Bang Qian 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2013年第7期827-834,共8页
We analyzed the B and V light curves of two EA-type binaries V211 and NV358 for the first time using the Wilson-Devinney code. Our analysis shows that V211 is a typical Algol-type binary and NV358 is a well detached b... We analyzed the B and V light curves of two EA-type binaries V211 and NV358 for the first time using the Wilson-Devinney code. Our analysis shows that V211 is a typical Algol-type binary and NV358 is a well detached binary system. As the two binaries are definite members of ω Centauri due to their proper motion, we estimated their physical parameters, obtaining M1 = 1.13 4±0.03 M⊙, R1 = 0.98±0.01 R⊙, M2 = 0.33 ±0.01 M⊙ and R2 = 0.92 ±0.01 R⊙ forV211; M1 = 1.304-0.05 M⊙, R1 = 1.03±0.01 R⊙, M2 = 0.58±0.02 M⊙ and R2 = 0.78±0.01 R⊙ for NV358. On the color-magnitude diagram of ω Centauri, V211 is located in the faint blue straggler region and its primary component is more massive than a star at the main-sequence turnoff. Therefore, V211 is a blue straggler and was formed by mass transfer from the secondary component to the primary. The age of NV358 is less than 1.93 Gyr, indicating that it is much younger than the first generation of stars in ω Centaufi. Like NV364 in ω Centaufi, NV358 should be a second-generation binary. 展开更多
关键词 galaxies: globular clusters: individual (ω Centauri) - stars: binaries:close - stars: binaries eclipsing - stars: blue stragglers - stars: individual (V211 NV358)
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Jet-dominated quiescent state in black hole X-ray binaries: the cases of A0620–00 and XTE J1118+480
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作者 Qi-Xiang Yang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2016年第4期79-86,共8页
The radiative mechanism of black hole X-ray transients (BHXTs) in their quiescent states (defined as the 2-10 keV X-ray luminosity ≤ 10^34 erg s-1) remains unclear. In this work, we investigate the quasi-simultan... The radiative mechanism of black hole X-ray transients (BHXTs) in their quiescent states (defined as the 2-10 keV X-ray luminosity ≤ 10^34 erg s-1) remains unclear. In this work, we investigate the quasi-simultaneous quiescent state spectrum (including radio, infrared, optical, ultraviolet and X-ray) of two BHXTs, A0620-00 and XTE J1118+480. We find that these two sources can be well described by a coupled accretion - jet model. More specifically, most of the emission (radio up to infrared, and the X-ray waveband) comes from the collimated relativistic jet. Emission from hot accretion flow is totally insignificant, and it can only be observed in mid-infrared (the synchrotron peak). Emission from the outer cold disk is only evident in the UV band. These results are consistent with our previous investigation on the quiescent state of V404 Cyg and confirm that the quiescent state is jet-dominated. 展开更多
关键词 ACCRETION accretion disks -- black hole physics -- X-rays: binaries -- stars: jets -- stars:individual (A0620-00 XTE J1118+480)
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Photometric Study of Three Short-Period Eclipsing Binaries from the ASAS Catalogue
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作者 J.A.Obu P.N.Okeke 《International Journal of Astronomy and Astrophysics》 2013年第2期123-130,共8页
We present the results of our study of three previously unstudied short-period eclipsing binaries, namely: ASAS 110609 ﹣ 2045.3, ASAS105331 ﹣ 7424.7, and ASAS 130057 + 2120.3. Using the visual (V)-band data obtained... We present the results of our study of three previously unstudied short-period eclipsing binaries, namely: ASAS 110609 ﹣ 2045.3, ASAS105331 ﹣ 7424.7, and ASAS 130057 + 2120.3. Using the visual (V)-band data obtained from the ASAS catalogue, the orbital and physical parameters of the systems were derived for the first time using the Wilson-Divenney (WD) codes. Our investigation revealed that ASAS 110609 ﹣ 2045.3 is a near-contact binary star of the W Uma type having an angle of inclination of 80° ± 1, a mass ratio of about 0.5, an orbital period of 0.2933 ± 0.0130 days, and an effective temperature in the range of 5800 K - 6200 K, making it a G2V-F7V spectral system. ASAS 105331 ﹣ 7424.7 was established to be an over-contact binary system of the W Uma type, inclined at 86° ± 2 to the line of sight, having a mass ratio of about 0.9, a period of 0.4825 ± 0.0002, and an effective temperature in the range of 5200 K - 5300 K, making it a K2V-K0V spectral system. A third light factor of just 0.1 was established for the system, however, no evidence of starspots or discs was inferred for either component. ASAS 130,057 + 2120.3 is a W Uma binary having a mass ratio of about 0.6 in a state of marginal contact. Its orbital inclination is 55° ± 1;the effective temperature is in the range of 6200 K - 6500 K, making it a F7V-F5V stellar system. The system showed evidence of third light, with a third light factor of 0.6, however, the presence of spots or discs could not be established for either component. The deduced period was 0.8930 ± 0.0014 days. None of the systems showed any evidence of the O’Connell effect on either component. 展开更多
关键词 binaries Eclipsing-Stars Starspots-Stars Fundamental Parameters-Individual ASAS 110609-2045.3 ASAS 105331-7424.7 ASAS 130057+2120.3
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Algebraic Solution for the Forward Displacement Analysis of the General 6-6 Stewart Mechanism 被引量:8
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作者 WEI Feng WEI Shimin +1 位作者 ZHANG Ying LIAO Qizheng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第1期56-62,共7页
The solution for the forward displacement analysis(FDA) of the general 6-6 Stewart mechanism(i.e., the connection points of the moving and fixed platforms are not restricted to lying in a plane) has been extensive... The solution for the forward displacement analysis(FDA) of the general 6-6 Stewart mechanism(i.e., the connection points of the moving and fixed platforms are not restricted to lying in a plane) has been extensively studied, but the efficiency of the solution remains to be effectively addressed. To this end, an algebraic elimination method is proposed for the FDA of the general 6-6 Stewart mechanism. The kinematic constraint equations are built using conformal geometric algebra(CGA). The kinematic constraint equations are transformed by a substitution of variables into seven equations with seven unknown variables. According to the characteristic of anti-symmetric matrices, the aforementioned seven equations can be further transformed into seven equations with four unknown variables by a substitution of variables using the Grobner basis. Its elimination weight is increased through changing the degree of one variable, and sixteen equations with four unknown variables can be obtained using the Grobner basis. A 40th-degree univariate polynomial equation is derived by constructing a relatively small-sized 9 × 9 Sylvester resultant matrix. Finally, two numerical examples are employed to verify the proposed method. The results indicate that the proposed method can effectively improve the efficiency of solution and reduce the computational burden because of the small-sized resultant matrix. 展开更多
关键词 general 6-6 Stewart mechanism forward displacement analysis (FDA) conformal geometric algebra (CGA) Gr6bner basis Sylvester resultant
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Variable binaries and variables in binaries in the Binary star DataBase
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作者 Dana Kovaleva Oleg Malkov Pavel Kaygorodov 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2019年第3期7-12,共6页
The Binary star DataBase(BDB, http://bdb.inasan.ru) combines data from catalogs of binary and multiple stars of all observational types. There is a number of ways for variable stars to form or to be a part of binary o... The Binary star DataBase(BDB, http://bdb.inasan.ru) combines data from catalogs of binary and multiple stars of all observational types. There is a number of ways for variable stars to form or to be a part of binary or multiple systems. We describe how such stars are represented in the database. 展开更多
关键词 astronomical data bases-stars binaries general-stars VARIABLES general
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Chaos in Compact Binaries with Frequency Map Analysis
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作者 Yi Xie Tian-Yi Huang 《Chinese Journal of Astronomy and Astrophysics》 CSCD 2006年第6期705-715,共11页
The dynamics of compact binaries is very complicated because of spin-orbit cou- pling and spin-spin coupling. With Laskar's frequency map analysis (FMA) and frequency diffusion as an indicator, we found that misali... The dynamics of compact binaries is very complicated because of spin-orbit cou- pling and spin-spin coupling. With Laskar's frequency map analysis (FMA) and frequency diffusion as an indicator, we found that misalignment of the spins and orbital angular momentum has a great effect on the dynamics, and for systems with different mass ratios β = m2/ml chaos occurs at different spin-orbit configurations. For equal-mass binaries (β = 1), chaos occurs when the spins nearly cancel each other out. For some other systems (for exampleβ - 1/2), the binaries are irregular, even chaotic, when the spins are perpendicular to the orbital angular momentum. For the case where gravitational radiation is taken into account, we give an analytic estimation for the frequency diffusion based on the decay of the orbit, which is roughly consistent with our simulations. This means the FMA is not suitable as a chaos indicator for weak chaotic cases with dissipative terms. 展开更多
关键词 celestial mechanics - (stars:) binaries (including multiple) CLOSE
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Reciprocating Magnetic Fields in the Pulsar Wind Observed from the Black Widow Pulsar J1720-0534
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作者 Chen-Chen Miao Victoria Blackmon +41 位作者 Wei-Wei Zhu Dong-Zi Li Ming-Yu Ge Xiao-Peng You Maura McLaughlin Di Li Na Wang Pei Wang Jia-Rui Niu M.Cruces Jian-Ping Yuan Jun-Tao Bai D.J.Champion Yu-Tong Chen Ming-Min Chi P.C.C.Freire Yi Feng Zhen-Ye Gan M.Kramer Fei-Fei Kou Yu-Xi Li Xue-Li Miao Ling-Qi Meng Chen-Hui Niu Sheng-Nan Sun Zhong-Yi Sun H.M.Tedila Shuang-Qiang Wang Qing-Dong Wu Jing-Bo Wang Zhi-Gang Wen Shen Wang Ya-Biao Wang Cheng-Jie Wang Meng-Yao Xue You-Ling Yue Mao Yuan Ju-Mei Yao Wen-Ming Yan Ru-Shuang Zhao Lei Zhang De Zhao 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第10期255-266,共12页
We report the radio observations of the eclipsing black widow pulsar J1720-0534, a 3.26 ms pulsar in orbit with a low mass companion of mass 0.029 to 0.034 M⊙. We obtain the phase-connected timing ephemeris and polar... We report the radio observations of the eclipsing black widow pulsar J1720-0534, a 3.26 ms pulsar in orbit with a low mass companion of mass 0.029 to 0.034 M⊙. We obtain the phase-connected timing ephemeris and polarization profile of this millisecond pulsar(MSP) using the Five-hundred-meter Aperture Spherical radio Telescope(FAST), the Green Bank Telescope(GBT), and the Parkes Telescope. For the first time from such a system, an oscillatory polarization angle change was observed from a particular eclipse egress with partial depolarization, indicating 10-milliGauss-level reciprocating magnetic fields oscillating in a length scale of 5 ×10^(3)km(assuming an orbital inclination angle of 90°) outside the companion's magnetosphere. The dispersion measure variation observed during the ingresses and egresses shows the rapid raising of the electron density in the shock boundary between the companion's magnetosphere and the surrounding pulsar wind. We suggest that the observed oscillatory magnetic fields originate from the pulsar wind outside the companion's magnetosphere. 展开更多
关键词 (stars:)pulsars:general (stars:)pulsars:individual(J1720-0534) (stars:)binaries:eclipsing
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Variable Stars in the 50BiN Open Cluster Survey.Ⅲ.NGC 884
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作者 Lin-Hong Wang Qian-Heng Nie +5 位作者 Kun Wang Xiao-Dian Chen Chun-Guang Zhang Li-Cai Deng Xiao-Bin Zhang Tian-Lu Chen 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第2期36-45,共10页
Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal ... Open clusters are the basic building blocks that serve as a laboratory for the study of young stellar populations in the Milky Way.Variable stars in open clusters provide a unique way to accurately probe the internal structure,temporal and dynamical evolutionary stages of individual stars and the host cluster.The most powerful tool for such studies is time-domain photometric observations.This paper follows the route of our previous work,concentrating on a photometric search for variable stars in NGC 884.The target cluster is the companion of NGC869,forming the well-known double cluster system that is gravitationally bound.From the observation run in 2016 November,a total of 9247 B-band CCD images and 8218Ⅴ-band CCD images were obtained.We detected a total of 15 stars with variability in visual brightness,including five Be stars,three eclipsing binaries,and seven of unknown types.Two new variable stars were discovered in this work.We also compared the variable star content of NGC 884 with its companion NGC 869. 展开更多
关键词 STARS variables general-(Galaxy:)open clusters and associations individual(… …)-(stars:)binaries general
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The Fifth Edition of the General Catalogue of Variable Stars:experiences in the constellation Centaurus
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作者 Nikolay N.Samus Elena N.Pastukhova +1 位作者 Olga V.Durlevich Elena V.Kazarovets 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2018年第7期93-100,共8页
We have recently announced that the General Catalogue of Variable Stars enters the stage of its fifth, purely electronic edition (GCVS 5.1). We have included 1408 variable stars in the constellation Centaurus in thi... We have recently announced that the General Catalogue of Variable Stars enters the stage of its fifth, purely electronic edition (GCVS 5.1). We have included 1408 variable stars in the constellation Centaurus in this new version, GCVS 5.1. Working on this revision, we applied current possibilities from data mining, suggested new variability types for many variable stars and found new light elements for a large number of periodic variables. This paper describes the work completed during the preparation of GCVS 5.1 for Centaurus and discusses in detail a number of the most astrophysically significant cases. 展开更多
关键词 catalogs - techniques photometric - stars variables general - binaries ECLIPSING
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Mass-accreting white dwarfs and type Ia supernovae
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作者 Bo Wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2018年第5期1-28,共28页
Type Ia supernovae(SNe Ia) play a prominent role in understanding the evolution of the Universe. They are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs(CO WDs) in binaries, al... Type Ia supernovae(SNe Ia) play a prominent role in understanding the evolution of the Universe. They are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs(CO WDs) in binaries, although the mass donors of the accreting WDs are still not well determined. In this article, I review recent studies on mass-accreting WDs, including H-and He-accreting WDs. I also review currently most studied progenitor models of SNe Ia, i.e., the single-degenerate model(including the WD+MS channel, the WD+RG channel and the WD+He star channel), the doubledegenerate model(including the violent merger scenario) and the sub-Chandrasekhar mass model.Recent progress on these progenitor models is discussed, including the initial parameter space for producing SNe Ia, the binary evolutionary paths to SNe Ia, the progenitor candidates for SNe Ia, the possible surviving companion stars of SNe Ia, some observational constraints, etc. Some other potential progenitor models of SNe Ia are also summarized, including the hybrid CONe WD model, the core-degenerate model, the double WD collision model, the spin-up/spin-down model and the model of WDs near black holes. To date, it seems that two or more progenitor models are needed to explain the observed diversity among SNe Ia. 展开更多
关键词 SUPERNOVAE general - binaries close - stars evolution - white dwarfs
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An algorithm to resolve γ-rays from charged cosmic rays with DAMPE 被引量:4
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作者 Zun-Lei Xu Kai-Kai Duan +18 位作者 Zhao-Qiang Shen Shi-Jun Lei Tie-Kuang Dong Fabio Gargano Simone Garrappa Dong-Ya Guo Wei Jiang Xiang Li Yun-Feng Liang Mario Nicola Mazziotta Maria Fernanda Munoz Salinas Meng Su Valerio Vagelli Qiang Yuan Chuan Yue Jing-Jing Zang Ya-Peng Zhang Yun-Long Zhang Stephan Zimmer 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2018年第3期25-36,共12页
The DArk Matter Particle Explorer(DAMPE),also known as Wukong in China,which was launched on 2015 December 17,is a new high energy cosmic ray and γ-ray satellite-borne observatory.One of the main scientific goals o... The DArk Matter Particle Explorer(DAMPE),also known as Wukong in China,which was launched on 2015 December 17,is a new high energy cosmic ray and γ-ray satellite-borne observatory.One of the main scientific goals of DAMPE is to observe Ge V-Te V high energy γ-rays with accurate energy,angular and time resolution,to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to γ-rays,it is challenging to identify γ-rays with sufficiently high efficiency,minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify γ-rays in DAMPE data based on Monte Carlo simulations,using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected γ-ray events at~10 Ge V amounts to less than 1% of the selected sample.Finally,we use flight data to verify the effectiveness of the method by highlighting known γ-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar. 展开更多
关键词 gamma rays general - instrumentation detectors - methods data analysis
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First photometric study of ultrashort-period contact binary 1SWASP J140533.33+114639.1 被引量:2
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作者 Bin Zhang Sheng-Bang Qian +2 位作者 Ri Michel Boonrucksar Soonthornthum Li-Ying Zhu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2018年第3期57-62,共6页
In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33+114639.1(hereafter J1405) in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devin... In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33+114639.1(hereafter J1405) in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney(W-D) code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9±0.5% and a mass ratio of q = 1.55±0.02. In order to explain the asymmetric light curves of the system,a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the(O-C) method,the variation of orbital period is studied using all the available times of minimum light. The(O-C) diagram reveals that the period is increasing continuously at a rate of d P/dt = +2.09×10^-7 d yr^-1,which can be explained by mass transfer from the less massive component to the more massive one. 展开更多
关键词 STARS binaries close - stars binaries eclipsing - stars individual (1SWASPJ140533.33+114639.1)
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