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ASAS J174406+2446.8 is identified as a marginal-contact binary with a possible cool third body

Research in Astronomy and Astrophysics 2020年第6期20卷 265-272页

作者： Xiang-Dong Shi Sheng-Bang Qian Lin-Jia Li Wei-Wei Na Xiao Zhou Yunnan Observatories Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China Yuxi Normal University Yuxi 653100China

ASAS J174406+2446.8 was originally found as aδScuti-type pulsating star with the period P=0.189068 d by ASAS ***,the LAMOST stellar parameters reveal that it is far beyond the red edge of pulsational instability strip on the log g-T diagram ofδScuti pulsating *** understand the physical properties of the variable star,we observed it by the 1.0-m Cassegrain reflecting telescope at Yunnan ***-color light curves in B,V,R_c and I_c bands were obtained and are analyzed by using the W-D *** is found that this variable star is a shallow-contact binary with an EB-type light curve and an orbital period of 0.3781 d rather than aδScuti *** is a W-subtype contact binary with a mass ratio of 1.135(±0.019)and a fill-out factor of 10.4%(±5.6)%.The situation of ASAS J174406+2446.8 resembles those of other EB-type marginal-contact binaries such as UU Lyn,ⅡPer and GW *** of them are at a key evolutionary phase from a semi-detached configuration to a contact system predicted by the thermal relaxation oscillation *** linear ephemeris was corrected by using 303 new determined times of light *** is detected that the O-C curve shows a sinusoidal variation that could be explained by the light-travel-time effect via the presence of a cool red *** present investigation reveals that some of theδScuti-type stars beyond the red edge of pulsating instability strip on the log g-T diagram are misclassified eclipsing *** understand their structures and evolutionary states,more studies are required in the future.

关键词： stars binaries close-stars binaries eclipsing-stars δScuti-stars individual(ASAS J174406+2446.8)

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On the narrow spectral feature at ∼3 TeV in the MAGIC spectrum of Mrk 501

arXiv

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arXiv 2021年

作者： Hu, Wen Yan, Dahai Department of Physics Jinggangshan University Jiangxi Province Ji'an343009 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences Kunming650011 China

Using a time-dependent one-zone leptonic model that incorporates both shock acceleration and stochastic acceleration processes, we investigate the formation of the narrow spectral feature at ∼ 3 TeV of Mrk 501 which was observed during the X-ray and TeV flaring activity in July 2014. It is found that the broadband spectral energy distribution (SED) can be well interpreted as the synchrotron and synchrotron-self-Compton emission from the electron energy distribution (EED) that is composed by a power-law (PL) branch and a pileup branch. The PL branch produces synchrotron photons which are scattered by the electrons of the pileup branch via inverse-Compton scattering and form the narrow spectral feature observed at the TeV energies. The EED is produced by two injection episodes, and the pileup branch in EED is caused by shock acceleration rather than stochastic acceleration. Copyright © 2021, The Authors. All rights reserved.

关键词： Stochastic systems

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The Red Supergiant Progenitor of Type II Supernova 2024ggi

arXiv

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arXiv 2024年

作者： Xiang, Danfeng Mo, Jun Wang, Xiaofeng Wang, Lingzhi Zhang, Jujia Lin, Han Chen, Liyang Song, Cuiying Liu, Liang-Duan Wang, Zhenyu Li, Gaici Department of Physics Tsinghua University Beijing100084 China National Astronomical Observatories CAS Beijing100101 China Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China Institute of Astrophysics Central China Normal University Wuhan430079 China Key Laboratory of Quark and Lepton Physics Central China Normal University Ministry of Education Wuhan430079 China University of Chinese Academy of Sciences Beijing100049 China

We present a detailed analysis of the progenitor and its local environment for the recently discovered type II supernova (SN) 2024ggi at a distance of about 6.7 Mpc, by utilizing the pre-explosion images from the Hubble Space Telescope (HST) and Spitzer Space Telescope. The progenitor is identified as a red, bright variable star, with absolute F814W-band magnitudes being -6.2 mag in 1995 to -7.2 mag in 2003, respectively, consistent with that of a normal red supergiant (RSG) star. Combining with the historical mid-infrared light curves, a pulsational period of about 379 days can be inferred for the progenitor star. Fitting its spectral energy distribution with stellar spectral models yields the stellar parameters of temperature, radius and bolometric luminosity as T*= 3290+19 -27 K, R*= 887+60 -51 Ro, and log(L/Lo)= 4.92+0.05 -0.04, respectively. The above parameters indicate that the progenitor of SN 2024ggi is consistent with the stellar evolutionary track of a solar-metallicity massive star with an initial mass of 13+1 -1 Mo. Moreover, our analysis indicates a relatively low mass loss rate (i.e., © 2024, CC BY.

关键词： Supernovae

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The carbon-to-H2, CO-to-H2 conversion factors and carbon abundance on kiloparsec scales in nearby galaxies

arXiv

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arXiv 2021年

作者： Jiao, Qian Gao, Yu Zhao, Yinghe Nanjing210023 China Department of Astronomy Xiamen University XiamenFujian361005 China Yunnan Observatories & Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650011 China

Using the atomic carbon [C i] (3P1 → 3P0) and [C i] (3P2 → 3P1) emission (hereafter [C i] (1−0) and [C i] (2−1), respectively) maps observed with the Herschel Space Observatory, and CO (1−0), Hi, infrared and submm maps from literatures, we estimate the [C i]-to-H2 and CO-to-H2 conversion factors of α[CI] (1−0), α[CI] (2−1), and αCO at a linear resolution ∼ 1 kpc scale for six nearby galaxies of M 51, M 83, NGC 3627, NGC 4736, NGC 5055, and NGC 6946. This is perhaps the first effort, to our knowledge, in calibrating both [C i]-to-H2 conversion factors across the spiral disks at spatially resolved ∼ 1 kpc scale though such studies have been discussed globally in galaxies near and far. In order to derive the conversion factors and achieve these calibrations, we adopt three different dust-to-gas ratio (DGR) assumptions which scale approximately with metallicity taken from precursory results. We find that for all DGR assumptions, the α[CI] (1−0), α[CI] (2−1), and αCO are mostly flat with galactocentric radii, whereas both α[CI] (2−1) and αCO show decrease in the inner regions of galaxies. And the central αCO and α[CI] (2−1) values are on average ∼ 2.2 and 1.8 times lower than its galaxy averages. The obtained carbon abundances from different DGR assumptions show flat profiles with galactocentric radii, and the average carbon abundance of the galaxies is comparable to the usually adopted value of 3 × 10−5. We find that both metallicity and infrared luminosity correlate moderately with the αCO whereas only weakly with either the α[CI] (1−0) or carbon abundance, and not at all with the α[CI] (2−1). © 2021, CC BY.

关键词： Galaxies

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A Method of Rapidly Deriving Late-type Contact Binary Parameters and Its Application in the Catalina Sky Survey

arXiv

引用

arXiv 2024年

作者： Wang, JinLiang Ding, Xu Li, JiaJia Xiong, JianPing Cheng, QiYuan Ji, KaiFan P.O. Box 110 Kunming650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China University of the Chinese Academy of Sciences Yuquan Road 19# Shijingshan Block Beijing100049 China

With the continuous development of large optical surveys, a large number of light curves of late-type contact binary systems (CBs) have been released. Deriving parameters for CBs using the the WD program and the PHOEBE program poses a challenge. Therefore, this study developed a method for rapidly deriving light curves based on the Neural Networks (NN) model combined with the Hamiltonian Monte Carlo (HMC) algorithm (NNHMC). The neural network was employed to establish the mapping relationship between the parameters and the pregenerated light curves by the PHOEBE program, and the HMC algorithm was used to obtain the posterior distribution of the parameters. The NNHMC method was applied to a large contact binary sample from the Catalina Sky Survey, and a total of 19,104 late-type contact binary parameters were derived. Among them, 5172 have an inclination greater than 70◦ and a temperature difference less than 400 K. The obtained results were compared with the previous studies for 30 CBs, and there was an essentially consistent goodness-of-fit (R2) distribution between them. The NNHMC method possesses the capability to simultaneously derive parameters for a vast number of targets. Furthermore, it can provide an extremely efficient tool for rapid derivation of parameters in future sky surveys involving large samples of CBs. Copyright © 2024, The Authors. All rights reserved.

关键词： Hamiltonians

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Photometric analysis of the dwarf nova SU UMa based on TESS

arXiv

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arXiv 2024年

作者： Liu, Wei Shi, Xiang-Dong Fang, Xiao-Hui Wang, Qi-Shan Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650216 China University of Chinese Academy of Sciences No.1 Yanqihu East Rd Huairou District Beijing101408 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China School of Mathematics Physics and Finance Anhui Polytechnic University Wuhu241000 China

We report the photometric analysis of SU UMa based on the observations of the Transiting Exoplanet Survey Satellite (TESS). TESS has released a large amount of data, which contains the light curves of a complete superoutburst and three normal outbursts of SU UMa. Based on the observations, the evolution of superhumps during the superoutburst was analyzed. By using the O - C method, the three stages were determined, and the superhump period for each stage was calculated. The mass ratio q = 0.137(1) was estimated based on the stage A superhump method. A periodic oscillation with a period of 2.17(9) days was found in the superhump minimum O - C diagram, which is related to the precession of the accretion disk. We investigated the frequency information of quasiperiodic oscillations (QPOs) in the light curves. An ultralong period QPO of 0.18 days at the time of normal outburst and two ultralong periods QPOs of 0.19 days and 0.285 days in quiescence were found. No QPO was found in the superoutburst. © 2024, CC BY.

关键词： Stars

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The study on transiting systems HAT-P-13, HAT-P-16 and WASP-32 through combining ground-based and TESS photometry

arXiv

引用

arXiv 2023年

作者： Sun, L. Gu, S. Wang, X. Bai, L. Schmitt, J.H.M.M. Perdelwitz, V. Ioannidis, P. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China Hamburger Sternwarte Universität Hamburg Gojenbergsweg 112 Hamburg21029 Germany Department of Physics Ariel University Ariel40700 Israel

High-precision transit photometry supplies ideal opportunities for detecting new exoplanets and characterizing their physical properties, which usually encode valuable information for unveiling the planetary structure, atmosphere and dynamical history. We present revised properties of three transiting systems (i.e., HAT-P-13, HAT-P-16 and WASP-32) through analyzing TESS photometry and ground-based transit observations, which were obtained at the 1m and 2.4m telescopes of Yunnan Observatories, China, and the 1.2m telescope of Hamburg Observatory, Germany, as well as the data in the literature. During modelling the transit light curves, Gaussian process is employed to account for the potential systematic errors. Through comprehensive timing analysis, we find that both HAT-P-13b and HAT-P-16b show significant timing variations (TTVs) that can be explained by apsidal precession. TTVs of WASP-32b may be led by a decaying orbit due to tidal dissipation or apsidal precession. However, the current observations can not rule out the origins of three systems’ TTVs from gravitational perturbations of close planetary companions conclusively. Copyright © 2023, The Authors. All rights reserved.

关键词： Photometry

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Asteroseismology of the pulsating extremely low-mass white dwarf SDSS J111215.82+111745.0: A model with p-mode pulsations consistent with the observations

arXiv

引用

arXiv 2022年

作者： Su, Jie Li, Yan Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China University of Chinese Academy of Sciences Beijing100049 China

SDSS J111215.82+111745.0 is the second pulsating extremely low-mass white dwarf discovered. Two short-period pulsations, 107.56 and 134.275 s, were detected on this star, which would be the first observed pressure mode (p-mode) pulsations observed on a white dwarf. While the two potential p-modes have yet to be confirmed, they make SDSS J111215.82+111745.0 an interesting object. In this work, we analyzed the whole set of seven periods observed on SDSS J111215.82+111745.0. We adopt three independent period-spacing tests to reveal a roughly 93.4 s mean period spacing of = 1 g-modes, which gives added credence to the = 1 identifications. Then we perform asteroseismic modeling for this star, in which the H chemical profile is taken as a variable. The stellar parameters M = 0.1650 ± 0.0137 Mo and Teff = 9750 ± 560 K are determined from the best-fit model and the H/He chemical profiles are also defined. The two suspected p-modes are also well represented in the best-fit model, and both the stellar parameters and the pulsation frequencies are in good agreement with the values derived from spectroscopy. © 2022, CC BY.

关键词： White dwarfs

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A method for estimating masses of W Ursae Majoris-type binaries

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Research in Astronomy and Astrophysics 2020年第12期20卷 243-253页

作者： Li-Na Lu Jin-Zhong Liu Deng-Kai Jiang Ya-Hui Wang Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Laboratory of New Energy and Materials Xinjiang Institute of EngineeringUrumqi 830091China

Masses of W Ursae Majoris-type(W UMa) binaries play a critical role in investigating stellar dynamical evolutionary status. In this paper, we combine the PARSEC(PAdova and TRieste Stellar evolution Code) with the Roche geometric model to provide a method to determine the masses of W UMa systems. To verify the validity of this method, we compile a sample of 140 spectrum binaries from the literature, which includes 76 W-and 64 A-subtype systems with reliable physical parameters. We find that the average fractional difference and the standard deviation(σM) of the residuals for W-subtype and Asubtype approximately amount to 15.66% and 0.1218, 16.03% and 0.2094, respectively. Meanwhile, we also perform detailed analyses in accordance with the orbital period, the effective temperatures and the mass ratio. We find that the method is more applicable to determine masses for W UMa systems with low effective temperature and short period.

关键词： stars:binaries:eclipsing W Ursae Majoris(W UMa)binaries masses

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Deep and low mass-ratio contact binaries and their third bodies

arXiv

引用

arXiv 2024年

作者： Liying, Zhu Shengbang, Qian Wenping, Liao Jia, Zhang Xiangdong, Shi Linjia, Li Fangbin, Meng Jiangjiao, Wang Azizbek, Matekov Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences No.1 Yanqihu East Rd Huairou District Beijing101408 China School of Physics and Astronomy Yunnan University Kunming650091 China Ulugh Beg Astronomical Institute Uzbekistan Academy of Sciences 33 Astronomicheskaya str. Tashkent100052 Uzbekistan

Deep and low mass-ratio contact binaries (DLMCBs) are believed to be in the final stage of their contact phase, potentially leading to the formation of fast-rotating single stars such as FK Com-type stars and blue stragglers, as well as luminous red novae. These systems serve as an excellent laboratory for studying stellar coalescence and merging processes. Our search for DLMCBs began in 2004 and has since identified a group of such systems. Together with that collected from the literature, more than 100 DLMCBs have been detected so far. Half of them have had their periods investigated based on O-C curves. Some have shown period increases, while others have exhibited period decreases. Among them, more than half DLMCBs have cyclic variations, suggesting the possibility of the existence of a third body orbiting around the DLMCBs. Furthermore, with more data obtained extending the span of the O-C curve, more cyclic variations could be detected. The high proportion of signs of the presence of third bodies makes them an essential factor to consider when studying the merger of contact binaries. Copyright © 2024, The Authors. All rights reserved.

关键词： Stars

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