The four-color ($B$ $V$ $R_c$ $I_c$) light curves of V776 Cas are presented and analyzed using the Wilson-Devinney (W-D) method. It is discovered that V776 Cas is an early F-type (F2V) overcontact binary with a very high contact degree ($ f=64.6\,\%$) and an extremely low mass ratio ($q=0.130$), which indicate that it is at the final evolutionary stage of cool short-period binaries. The mass of the primary and secondary stars are calculated to be $M_1 = 1.55(\pm0.04)M_\odot$, $M_2 = 0.20(\pm0.01)M_\odot$. V776 Cas is supposed to be formed from an initially detached binary system via the loss of angular momentum due to the magnetic wind. The initial mass of the present primary and secondary components are calculated to be $M_{1i} = 0.86(\pm0.10)M_\odot$ and $M_{2i} = 2.13(\pm0.04)M_\odot$. The observed-calculated ($O$-$C$) curve exhibits a cyclic period variation, which is due to the light-travel time effect (LTTE) caused by the presence of a third component with a period of 23.7 years. The mass of the third component is estimated to be $M_3 = 1.04(\pm0.03)M_\odot$ and the orbital inclination of the third component is calculated to be $i' = 33.1^{\circ}$. The distance of the binary system to the mass center of the triple system is calculated to be $a'_{12} = 3.45AU$. The presence of the close-in tertiary component may play an important role in the formation and evolution of this binary system by drawing angular momentum from the central system.
The unusual quadruple system HD 91962 with a "planetary" architecture
HD 91962是一个罕见的四重恒星系统，其中三颗伴星围绕主恒星旋转，周期分别为170.3天、8.85年和205年。两个外层轨道几乎共面，所有轨道都有小的偏心率。我们改进了外双星的可见轨道，确定了中间8.8年双星的光谱干涉轨道和内双星的光谱轨道。中轨道和内轨道可能锁定在1：19的共振中，外周期和中周期的比值约为23。估算了所有组成部分的质量（由内向外：1.14，0.32，0.64，0.64太阳质量），动力学视差为27.4 ± 0.6质量。我们推测，这个多重系统起源于一个孤立的核心崩溃和同伴迁移在一个耗散盘。具有类似特征（共面性、小偏心率和约20的周期比）的其他多重系统是已知的。
CW Cas: A solar-type contact binary system with an unseen third companion in a hierarchical quadruple system
Yunnan Observatories, Chinese Academy of Sciences（中国科学院云南天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Ulugh Beg Astronomical Institute, Uzbekistan Academy of Sciences（乌兹别克斯坦科学院乌鲁格别克天体物理研究所）
Double-close-binary quadruples (2+2 systems) are hierarchical systems of four stars where two short-period binary systems move around their common center of mass on a wider orbit. Using Gaia Early Data Release 3, we search for comoving pairs where both components are eclipsing binaries. We present eight 2+2 quadruple systems with inner orbital periods of $<$ 0.4 days and with outer separations of $\gtrsim 1000$ AU. All but one system are newly discovered by this work, and we catalog their orbital information measured from their light curves. We find that the occurrence rate of 2+2 quadruples i…
The $VRC$ light curves were regularly measured for the eclipsing binary NSVS 7453183 as a part of our long-term observational project for studying of low-mass eclipsing binaries with a short orbital period and surface activity. The TESS light curve solution in Phoebe results to the detached configuration, where the temperature of primary component was adopted to $T_1$ = 4300 K according to the SED approximation. It gives us $T_2 =$ 4080 $\pm$ 100 K for the secondary component. The spectral type of the primary component was estimated to be K6 and the photometric mass ratio was derived $q = 0.86…
Period and period change measurements for 143 SuperWASP eclipsing binary candidates near the short-period limit and discovery of a doubly eclipsing quadruple system
Spectroscopic Characterization of WD J000801.25-350450 and its Two Co-Moving Companions
Backyard Worlds: Planet 9（后院行星九）；School of Physical Sciences, The Open University（开放大学物理科学学院）；School of Physics and Astronomy, University of Leicester（莱斯特大学物理与天文学院）；Department of Physics, Università degli Studi di Trieste（的里雅斯特大学物理系）；INAF-Osservatorio Astronomico di Trieste（意大利国家天体物理研究所的里雅斯特天文台）；United States Naval Observatory, Flagstaff Station（美国海军天文台弗拉格斯塔夫站）；Planétarium de Montréal, Espace pour la Vie（蒙特利尔生物圈博物馆）；Trottier Institute for Research on Exoplanets, Université de Montréal（蒙特利尔大学特罗蒂尔系外行星研究所）；Department of Astrophysics, American Museum of Natural History（美国自然历史博物馆天体物理学部）；NSF National Optical-Infrared Astronomy Research Laboratory（美国国家光学-红外天文研究实验室）；Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center（NASA戈达德太空飞行中心系外行星与恒星天体物理学实验室）；Department of Astronomy & Astrophysics, UC San Diego（加州大学圣地亚哥分校天文与天体物理学系）
There is an ongoing debate on whether hot jupiter hosts are more likely to be found in wide binaries with separations of $\gtrsim 100$ AU. In this paper, we search for comoving, very wide companions with separations of $10^3-10^4$ AU for hot jupiter hosts and main-sequence contact binaries in Gaia DR2, and compare the very wide companion fractions with their object-by-object-matched field star samples. We find that $11.9\pm 2.5$% of hot jupiter hosts and $14.1\pm 1.0$% of contact binaries have companions at separations of $10^3-10^4$ AU. While the very wide companion fraction of hot jupiter ho…
The first B-, V-, Rc-, and Ic-band light curves of CSS J022914.4+044340 are presented and analyzed. It is found that CSS J022914.4+044340 is a low mass ratio (0.198 +- 0.005) deep (63.7 +- 7.9%) contact binary, indicating that it has been already at the end evolutionary stage of tidally-locked evolution via magnetized wind. Because of the totally eclipsing character, the photometric solutions are reliable. The temperature and the metallicity are determined from the spectroscopic data as T = 5855 +- 15 K, and [Fe/H] = -0.842 +- 0.031, respectively. Based on the parallax of Gaia EDR3, the physic…
Recent detections of gravitational waves from mergers of neutron stars (NSs) and black holes (BHs) in the low and high-end mass gap regimes pose a puzzle to standard stellar and binary evolution theory. Mass-gap mergers may originate from successive mergers in hierarchical systems such as quadruples. Here, we consider repeated mergers of NSs and BHs in stellar 2+2 quadruple systems, in which secular evolution can accelerate the merger of one of the inner binaries. Subsequently, the merger remnant may interact with the companion binary, yielding a second-generation merger. We model the initial …
In this study we identify 11 Kepler systems (KIC 5255552, 5653126, 5731312, 7670617, 7821010, 8023317, 10268809, 10296163, 11519226, 11558882 and 12356914) with a "flip-flop" effect in the eclipse timing variations O-C diagrams of the systems, report on what these systems have in common and whether these systems are dynamically stable. These systems have previously reported high eccentric binary stars with highly eccentric third bodies/outer companions. We find that all of the additional bodies in the system are dynamically stable for the configurations previously reported and are therefore li…
Know the Star, Know the Planet. III. Discovery of Late-Type Companions to Two Exoplanet Host Stars
我们讨论了两个拥有已知系外行星的多恒星系统：HD 2638和30 Ari B。自适应光学图像显示了两颗恒星的额外伴星。我们在Palomar天文台收集了Robo-AO和PALM-3000自适应光学系统的多历元图像，并提供了相对测光和天体测量。天体测量表明，伴星与它们各自的主星有共同的自行。这两颗新的伴星都预计与系外行星宿主恒星的距离小于30 AU。使用投影的分离来计算新伴星的轨道周期，HD 2638的周期为130年，而30 Ari B的周期为80年。以前的研究表明，真实的周期很可能在这些估计值的三倍之内。30 Ari的额外组成部分使其成为第二个确认的四重系统，已知拥有系外行星。HD 2638拥有一颗热木星，新伴星的发现加强了热木星和双星之间的联系。我们把系统的颜色星等图，并得出质量的同伴，原来是大约0.5太阳质量的恒星。
Spectroscopic and Decade-long Photometric Observations of the Contact Binary V2790 Ori: Evidence for a Brown Dwarf Companion and a Solar-like Magnetic Activity Cycle
We present the latest results of our ongoing multiplicity study of (Community) TESS Objects of Interest, using astro- and photometric data from the ESA-Gaia mission, to detect stellar companions of these stars and to characterize their properties. In total, 113 binary, 5 hierarchical triple star systems, as well as one quadruple system were detected among 585 targets surveyed, which are all located at distances closer than about 500pc around the Sun. As proven with their accurate Gaia EDR3 astrometry the companions and the targets are located at the same distance and share a common proper moti…
The binary status of gamma-Cas stars has been discussed while theoretically examining the origin of their peculiar X-ray emission. However, except in two cases, no systematic radial velocity monitoring of these stars had been undertaken yet to clarify their status. We now fill this gap using TIGRE, CARMENES, and UVES high-resolution spectroscopy. Velocities were determined for 16 stars, revealing shifts and/or changes in line profiles. The orbit of six new binaries could be determined: the long periods (80-120d) and small velocity amplitudes (5-7km/s) suggest low mass companions (0.6-1 M$_{\od…
Reaching the boundary between stellar kinematic groups and very wide binaries. III. Sixteen new stars and eight new wide systems in the beta Pictoris moving group
Distinguishing between light curves of ellipsoidal variables with massive dark companions, contact binaries, and semidetached binaries using principal component analysis
This study aims at timing the eclipses of the binary star TU UMi. The times of minima are taken from the literature, from our observations in April 2004 and from TESS observations between 2019 and 2022. The orbital period analysis of the system indicates that there is a cyclic oscillation with an amplitude of 0.0081d and a period of 9.03 yr, accompanied by a continuous decrease at a rate of $dP/dt =-1.12 \times 10^{-7}\,\mathrm{d}\, \mathrm{yr}^{-1}$. We study the secular evolution of the orbital period of the system and the possibility of the existence of a third companion or the magnetic act…
We aim to hunt for massive binaries hosting a black hole companion (OB+BH) and establish the natal mass-ratio distribution of massive stars at the subsolar metallicity environment of the Large Magellanic Cloud (LMC). We use the shift-and-add grid disentangling technique to characterize the hidden companions in 51 SB1 O-type and evolved B-type binaries in the LMC monitored in the framework of the Tarantula Massive Binary Monitoring (TMBM). Out of the 51 SB1 systems, 43 (84%) are found to have non-degenerate stellar companions, of which 28 are confident detections, and 15 are less certain (SB1: …
Modelling the radio emission from Cyg OB2 #5: a quadruple system?
利用甚大天线阵对天鹅座OB2#5超巨星双星进行了20年的50次射电观测，以确定先前探测到的射电辐射的位置和特征。该系统的射电辐射由一个与双星相关的主成分和一个非热源（NE）组成，该非热源被认为是双星的恒星风和NE的B型星（D星）的恒星风之间的风碰撞区（WCR）。NE显示没有变化的证据，在23个历元，它是从主要的无线电组件单独解决，表明可变的排放产生的主要。由于NE是不变的，现在可以很好地确定来自主要的无线电通量第一次，特别是在观测，不解决的主要和NE分量。主星的射电辐射变化周期为6.7+/-0.3年，这可以用一个简单的模型来描述，即在双星的恒星风包层内运行的非热源。这样的模型意味着存在第三颗未被发现的恒星伴星（恒星C），以6.7年的周期绕着6.6天的双星运行。可变的非热辐射来自恒星C和双星系统之间的WCR，或者可能直接来自恒星C。该模型给出天鹅座OB 2 #5的质量损失率为3.4 x 10^{-5}太阳质量/年，对于超巨星来说异常高，与WR星相当，并且与异常强的He I 1.083微米发射线一致，也散发着WR星的气味。对径向速度观测的检验表明，双星的反射运动是由于恒星C。NE和星D的性质也被检查。（节略）
The Binary-Binary Hierarchical System XY Leo: A Laboratory for Stellar Activity and Concealed Companions
Institute of Astronomy, The Observatories（天文研究所，天文台）；Ege University（埃ege大学）；Department of Astronomy and Space Sciences, Faculty of Science, Ege University（埃ege大学理学院天文学与空间科学系）
This work studies the significance of the lightcurve intrinsic variability in the numerical modeling of contact binaries. Using synthetic light curves we are showing that the starspot-based intrinsic variability increases the apparent mass ratio by $Δq=5$%. For systems with orbital period $P>0.3 d$ the effect of intrinsic variability averaged over long time cancels each other out with the Kepler Mission-like phase smearing. Further, we analyse 47 totally eclipsing Kepler Mission contact binaries. We found a sharp cutoff of the intrinsic variability at P = 0.45 d. With the light curve numerical…
The VRI passbands light curves of V344 Lac were presented and analyzed by using the latest version of the W-D code. The observed spectrum reveals that V344 Lac is not an A3 type but would be a later F type star according to the yielded temperature. The results of solution show that V344 Lac is an A-subtype contact binary, with a mediate photometric mass ratio of 0.387(0.003) and a mediate contact factor of 44.6(3.0)%. Based on the parallax given by Gaia, the parameters of the components are estimated as: M1 = 1.16 Ms, M2 = 0.45 Ms, R1 = 1.31 Rs, R2 = 0.88 Rs, L1 = 2.512 Ls, L2 = 1.057 Ls. The …
WZ Cygni: a Marginal Contact Binary in a Triple System?
介绍了2007年和2008年两个观测季共22个夜晚对天鹅座WZ进行的多波段CCD测光。我们的光变曲线的综合表明，该系统是在填充因子为4.8%和1447 K的温差差的热接触。包括我们的40个定时测量，共371次的最小光跨越超过112年的一个周期的研究。对$O$ - $C$图的详细分析表明，轨道周期是由向上的抛物线和正弦曲线组合而成的。向上的抛物线意味着周期的连续增加，表明一些恒星质量从质量较小的主星向质量较大的主星进行热转移的速率约为5.80 $\times10^{-8}$ M $_\odot$ yr $^{-1}$。周期为47.9年，半振幅为0.008天的正弦变化最有可能被解释为光旅行时间效应，这是由于存在一个低质量的M型第三伴星，其投影质量为$M_3 \sin i_3$ =0.26 M $_\odot$。我们从食双星的绝对尺度上考察了天鹅座WZ的演化状况。它属于边缘接触双星系统，由一颗光谱型为F4的大质量主星和一颗光谱型为K1的伴星组成。
W UMi is a near contact, semi-detached, double-lined eclipsing binary star with an orbital period of 1.7 days. Simultaneous analysis of new BVR multi-color light curves and radial velocity data yields the main astrophysical parameters of the binary and its component stars. We determined mass and radius to be M$_{1}$=3.22$\pm$0.08 M$_{\odot}$, R$_{1}$=3.63$\pm$0.04 R$_{\odot}$ for the primary star and M$_{2}$=1.44$\pm$0.05 M$_{\odot}$, R$_{2}$=3.09$\pm$0.03 R$_{\odot}$ for the secondary star. Based on analysis of mid-eclipse times, variation in the orbital period is represented by a cyclic term…
