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Spectroscopic triples and a chance alignment. A solution for a problem of suspicious mass ratios for SB2s from Wilson method.

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arXiv 2023年

作者： Kovalev, Mikhail Chen, Xuefei Han, Zhanwen Yunnan Observatories China Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Sternberg Astronomical Institute M. V. Lomonosov Moscow State University Leninskie Gory Moscow119991 Russia Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China

We selected three double-lined spectroscopic binary systems which have extreme mass ratios, if measured using the Wilson method. We analysed medium resolution spectroscopic observations and space-based photometry and find that all these systems are not SB2, but rather triple systems and a chance alignment of another star with SB1 that have an unseen component. Therefore suspicious mass ratios determined by the Wilson method for some double-lined spectroscopic binary systems aren’t correct as these systems are more complex. Copyright © 2023, The Authors. All rights reserved.

关键词： Stars

Type Ia Supernova Explosions in Binary Systems: A Review

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arXiv 2023年

作者： Liu, Zheng-Wei Röpke, Friedrich K. Han, Zhanwen Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China University of Chinese Academy of Science Beijing100012 China Zentrum für Astronomie Universität Heidelberg Institut für Theoretische Astrophysik Philosophenweg 12 Heidelberg69120 Germany Heidelberger Institut für Theoretische Studien Schloss-Wolfsbrunnenweg 35 Heidelberg69118 Germany

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 (CSM) interaction, surviving companion stars, late-time spectra and photometry, polarization signals, and supernova remnant properties, etc. Despite the efforts from both the theoretical and observational side, the 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 the improvement of 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 (JWST), Gaia and the Zwicky Transient Facility (ZTF), and upcoming extensive projects with the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) and the Square Kilometre Array (SKA) will allow us to conduct not only studies of individual SNe Ia in unprecedented detail but also systematic investigations for di

关键词： Explosions

The Distribution of Semi-Detached Binaries. *** Efficient Pipeline

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arXiv 2023年

作者： Xiong, Jianping Ding, Xu Li, Jiadong Ge, Hongwei Cheng, Qiyuan Ji, Kaifan Han, Zhanwen Chen, Xuefei Yunnan Observatories Chinese Academy of Sciences 396 YangFangWang Guandu District Kunming650216 China Max-Planck-Institut für Astronomie Königstuhl 17 HeidelbergD-69117 Germany Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China

Semi-detached binaries are in the stage of mass transfer and play a crucial role in studying mass transfer physics between interacting binaries. Large-scale time-domain surveys provide massive light curves of binary systems, while Gaia offers high-precision astrometric data. In this paper, we develop, validate, and apply a pipeline that combines the MCMC method with a forward model and DBSCAN clustering to search for semi-detached binary and estimate its inclination, relative radius, mass ratio, and temperature ratio using light curve. We train our model on the mock light curves from PHOEBE, which provides broad coverage of light curve simulations for semi-detached binaries. Applying our pipeline to TESS sectors 1-26, we have identified 77 semi-detached binary candidates. Utilizing the distance from Gaia, we determine their masses and radii with median fractional uncertainties of ∼26% and ∼7%, respectively. With the added 77 candidates, the catalog of semi-detached binaries with orbital parameters has been expanded by approximately 20%. The comparison and statistical results show that our semi-detached binary candidates align well with the compiled samples and the PARSEC model in Teff-L and M-R relations. Combined with the literature samples, comparative analysis with stability criteria for conserved mass transfer indicates that ∼ 97.4% of samples are undergoing nuclear-timescale mass transfer, and two samples (GO Cyg and TIC 454222105) are located within the limits of stability criteria for dynamical- and thermal-timescale mass transfer, which are currently undergoing thermal-timescale mass transfer. Additionally, one system (IR Lyn) is very close to the upper limit of delayed dynamical-timescale mass transfer. Copyright © 2023, The Authors. All rights reserved.

关键词： Mass transfer

The environments of Type Ia supernovae with different relative equivalent width of Si II feature in their spectra

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arXiv 2022年

作者： Meng, Xiang-Cun Zhang, Ju-Jia Zhao, Xu-Lin Li, Li-Ping Wang, Xiao-Feng 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 Science Tianjin University of Technology Tianjin300384 China University of Chinese Academy of Sciences Beijing100049 China Tsinghua University Beijing100084 China

Although type Ia supernovae are so important in many astrophysical field, e.g. in cosmology, their explosion mechanism and progenitor system are still unclear. In physics, the relative equivalent width (REW) of the Si II 635.5 nm absorption feature reflects the velocity interval of silicon in the supernova ejecta and then may provide constraints on the explosion mechanism of SNe Ia. In this paper, we divide the SNe Ia into broad line (BL) and normal line (NL) subsamples based on their REW of Si II 635.5 nm absorption lines around maximum light, and find that the BL SNe Ia have a dimmer mean brightness than NL ones, which possibly results from their different metallicities. However, based on the pixel statistics study on the environments of two subsamples, we do not find any significant potential difference on the environments between BL and NL SNe Ia, which implies that the explosion mechanism of SNe Ia could be independent of their progenitor populations. Copyright © 2022, The Authors. All rights reserved.

关键词： Supernovae

The origin of the soft x-ray excess in the seyfert 1.5 Galaxy ESO 362-G18

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arXiv 2021年

作者： Zhong, Xiao-Gu Wang, Jian-Cheng Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China

We review the Seyfert 1.5 Galaxy ESO 362-G18 for exploring the origin of the soft X-ray excess. The Warm Corona and Relativistic Reflection models are two main scenarios to interpret the soft X-ray excess in AGNs at present. We use the simultaneous X-ray observation data of XMM-Newton and NuSTAR on Sep. 24th, 2016 to perform spectral analysis in two steps. First, we analyze the time-average spectra by using Warm Corona and Relativistic Reflection models. Moreover, we also explore the Hybrid model, Double Reflection model and Double Warm Corona model. We find that both of Warm Corona and Relativistic Reflection models can interpret the time-average spectra well but cannot be distinguished easily based on the time-averaged spectra fit statistics. Second, we add the RMS and covariance spectra to perform the spectral analysis with time-average spectra. The result shows that the warm corona could reproduce all of these spectra well. The the hot, optical thin corona and neutral distant reflection will increase their contribution with the temporal frequency, meaning that the corona responsible for X-ray continuum comes from the inner compact X-ray region and the neutral distant reflection is made of some moderate scale neutral clumps. © 2021, CC BY.

关键词： Galaxies

The radius variations of accreting main sequence stars and mass transfer instability

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arXiv 2024年

作者： Zhao, Zi-Qi Li, Zhen-Wei Xiao, Lin Ge, Hong-Wei Han, Zhan-Wen Department of Physics Hebei University Baoding071002 China Hebei Key Laboratory of High-precision Computation and Application of Quantum Field Theory Baoding071002 China Hebei Research Center of the Basic Discipline for Computational Physics College of Physics Science and Technology Hebei University Baoding071002 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Science China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China University of the Chinese Academy of Science Yuquan Road 19 Shijingshan Block Beijing100049 China

Many previous works studied the dynamical timescale mass transfer stability criteria based on the donor response with neglecting the stellar structure of the accretor. In this letter, we investigate the radial response of accretors with mass accumulation and its effect on the binary mass transfer stability. We perform a series of detailed stellar evolution simulations with different types of accretors and obtain the radial variations of stars accreting at different rates. Since the time within which the donor loses half of the original mass has a correlation with the donor mass, we approximately obtain the mean mass transfer rate as a function of mass ratio. Assuming that the common envelope (CE) phase occurs if the accretor radius exceeds the outer Roche lobe radius, we obtain the critical mass ratio of dynamically unstable mass transfer. We find the critical mass ratios for donors filling their Roche lobes at the Main Sequence (MS) and Hertzsprung Gap (HG) stages are smaller than that derived from the radial response of the donor in the traditional way. Our results may suggest that the binary is easier to enter into the CE phase for a donor star at the MS or HG stage than previously believed. Copyright © 2024, The Authors. All rights reserved.

关键词： Mass transfer

Detection of Contact Binary Candidates Observed By TESS Using Autoencoder Neural Network

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arXiv 2024年

作者： Ding, Xu Song, ZhiMing Wang, ChuanJun 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 School of Information Yunnan University of Finance and Economics Kunming China Yunnan Key Laboratory of Service Computing Kunming China University of the Chinese Academy of Sciences Yuquan Road 19# Shijingshan Block Beijing100049 China

Contact binary may be the progenitor of a red nova that eventually produces a merger event and have a cut-off period around 0.2 days. Therefore, a large number of contact binaries is needed to search for the progenitor of red novae and to study the characteristics of short-period contact binaries. In this paper, we employ the Phoebe program to generate a large number of light curves based on the fundamental parameters of contact binaries. Using these light curves as samples, an autoencoder model is trained, which can reconstruct the light curves of contact binaries very well. When the error between the output light curve from the model and the input light curve is large, it may be due to other types of variable stars. The goodness of fit (R2) between the output light curve from the model and the input light curve is calculated. Based on the thresholds for global goodness of fit (R2), period, range magnitude, and local goodness of fit (R2), a total of 1322 target candidates were obtained. © 2024, CC BY.

关键词： Stars

Two high-amplitude δ Scuti-γ Doradus hybrids constrained by the radial fundamental p and equally spaced g modes

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arXiv 2024年

作者： Chen, Xinghao Zhang, Xiaobin Li, Yan Su, Jie Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China University of Chinese Academy of Sciences Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China

Based on 2-minute cadence TESS data, we investigate pulsations of TIC 65138566 and TIC 139729335 and discover them to be two new HADS stars with equally spaced g modes. We recognize the radial fundamental mode f1 = 18.3334 c/d and the first overtone f3 = 23.6429 c/d for TIC 65138566, and identify the highest peak f1 = 19.0955 c/d as the radial fundamental mode for TIC 139729335. For g modes, both stars display a regular period spacing of 2413 s. Through detailed seismological analysis, we deduce that these period spacing patterns correspond to modes with = 1. Moreover, our analysis reveals that with the increase in masses and metallicities, the star should display a higher degree of evolution to match a specific period spacing Π0. Conversely, the star should have a lower extent of evolution to match the radial fundamental mode. These two contradictory behaviors allow us to precisely obtain stellar physical parameters. TIC 65138566 and TIC 139729335 are determined to be two main sequence stars that have almost the same range of masses and metallicities, with M = 1.36 ± 0.06 M☉ and Z = 0.005 ± 0.002. The hydrogen abundance in the core of TIC 65138566 is estimated to be about 0.28, while TIC 139729335 has a slightly higher value of around 0.31. Finally, we suggest that the HADS δ Scuti-γ Doradus star TIC 308396022 is a main sequence star with M = 1.54 ± 0.08 M☉, Z = 0.007 ± 0.001, and Xc = 0.18 ± 0.02. Copyright © 2024, The Authors. All rights reserved.

关键词： Stars

Photometric Analysis of the Dwarf Nova Su Uma Based on Tess

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SSRN

SSRN 2023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 ofthe Transiting Exoplanet Survey Satellite (TESS). TESS has released a large amount of data, which contain the light curves of a complete superoutburst and three normal outbursts of SU UMa. The evolution of superhumps during the superoutburst were analyzed. By using O - C method the three stages were determined and the superhump period for each stage were 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 QPOs in the light curves. An ultra-long period QPO of 0.18 days at the time of normal outburst and two ultra-long periods QPOs of 0.19 days and 0.285 days in quiescence were found. No QPO was found in the superoutburst. © 2023, The Authors. All rights reserved.

关键词： Stars