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Eclipsing binary XZ CMi in a hierarchical quadruple system

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Research in Astronomy and Astrophysics 2020年第8期20卷 307-315页

作者： Zhi-Hua Wang Li-Ying Zhu Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

The new complete BV Rc Ic light curves and spectra of the short-period eclipsing binary XZ CMi are *** results from the combined analysis based on the photometric and spectroscopic data show that XZ CMi is a near contact binary with the secondary component filling its critical Roche lobe while the primary filling 91%of its Roche *** investigation of the O-C diagram reveals that its orbital period is continuously increasing,which is consistent with the derived configuration and caused by the mass transfer from the less massive star to the more massive *** addition,an obvious periodic modulation with the amplitude of0.0187(±0.0016)d and a high eccentric of 0.86(±0.04)is detected,which could be the results of the light time effect as a third star with the mass no less than 0.42(±0.09)M⊙orbiting around the central eclipsing binary once every 95.7(±2.1)***,we found a visual companion star at 2.4′′east by south of this system at a much greater distance by direct *** large third light contribution found from the light curve analysis could be well explained by the existence of the third star and the fourth visual *** similar parallax and proper motion imply that the components of this hierarchical quadruple system might be bounded by *** observations for two visual components were carried out by the LAMOST and 2.16 m telescopes,*** different values of[Fe/H]suggest that they were not born from the same ***,XZ CMi system is an interesting and important target to study the formation of the multiple stars.

关键词： binaries:close binaries:eclipsing stars:individual(XZ CMi)

The Red Supergiant Progenitor of Type II Supernova 2024ggi

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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

Prominence detection and chromosphere feature on the prototype RS CVn of active binary systems

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arXiv 2024年

作者： Cao, Dongtao Gu, Shenghong Wolter, U. Mittag, M. Schmitt, J.H.M.M. Gao, Dongyang Hu, Shaoming 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 HamburgD-21029 Germany Shandong Provincial key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space Sciences Shandong University Weihai264209 China

We present a study of high-resolution spectra of RS Canum Venaticorum (RS CVn), a prototype of active binary systems. Our data were obtained from 1998 to 2017 using different telescopes. We analyze the chromospheric activity indicators Ca ii IRT, Hα, Na i D1, D2 doublet, He i D3, and Hβ using a spectral subtraction technique. The chromospheric emission stems mainly from the K2 IV primary star, while the F5 V secondary star only shows weak emission features in a few of our spectra. We find excess absorption features in the subtracted Hα lines and other activity indicators from spectra taken near primary eclipse, which we ascribe to prominence-like material associated with the primary star. We estimate size limits of these tentative prominences based on the geometry of the binary system, and investigate the physical properties of the strongest prominence. An optical flare, characterized by He i D3 line emission, together with stronger emission in other activity lines, was detected. The flare energy is roughly comparable to strong flares observed on other RS CVn-type stars. The chromospherically active longitudes of RS CVn most frequently appear near the two quadratures of the system and display changes between observing runs, which indicates an ongoing evolution of its active regions. Copyright © 2024, The Authors. All rights reserved.

关键词： Chromophores

Does Nature allow formation of ultra-compact black hole X-ray binaries via accretion-induced collapse of neutron stars?

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arXiv 2023年

作者： Chen, Hai-Liang Tauris, Thomas M. Chen, Xuefei Han, Zhanwen Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Department of Materials and Production Aalborg University Skjernvej 4A Aalborg ØstDK-9220 Denmark University of the Chinese Academy of Sciences Yuquan Road 19 Shijingshan Block Beijing100049 China

The formation path to ultra-compact X-ray binaries (UCXBs) with black hole (BH) accretors is still unclear. In the classical formation scenario, it is difficult to eject the massive envelope of the progenitor star of the BH via common envelope process. Given that some neutron stars (NSs) in binary systems evidently have birth masses close to ∼ 2.0 M☉, we explore here the possibility that BH-UCXBs may form via accretion-induced collapse (AIC) of accreting NSs, assuming that these previously evolved in LMXBs to masses all the way up to the maximum limit of a NS. We demonstrate this formation path by modelling a few cases of NS-UCXBs with initial NS masses close to the maximum mass of a NS that evolve into BH-UCXBs after the NS accretes material from its He WD companion. We follow the evolution of the post-AIC BH-UCXB and, based on simple arguments, we anticipate that there is about one BH-UCXB with an AIC origin and a He WD donor within the current sample of known UCXBs and that 2-5 such BH-UCXBs may be detected in gravitational waves by LISA. In addition, we find that the X-ray luminosity of NS-UCXBs near their orbital period minimum exceeds ∼ 1039 erg s−1 and thus such systems may appear as ultraluminous X-ray sources. © 2023, CC BY.

关键词： Gravity waves

The formation of neutron star systems through accretion-induced collapse in white-dwarf binaries

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Research in Astronomy and Astrophysics 2020年第9期20卷 135-158页

作者： Bo Wang Dongdong Liu Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

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)***,there has been no direct detection of any AIC event so far,even though there exists a lot of indirect observational ***,the evolutionary pathways resulting in NS formation through AIC are still not thoroughly *** 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 *** 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 *** 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,*** theoretical and

关键词： binaries:close white dwarfs supernovae:general stars:neutron stars:evolution

Taxonomic analysis of asteroids with artificial neural networks

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arXiv 2023年

作者： Luo, Nanping Wang, Xiaobin Gu, Shenghong Penttilä, Antti Muinonen, Karri Liu, Yisi Yunnan Observatories CAS Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Department of Physics University of Helsinki P.O. box 64 FI-00014 Finland Deep Space Exploration Laboratory Beijing100043 China

We study the surface composition of asteroids with visible and/or infrared spectroscopy. For example, asteroid taxonomy is based on the spectral features or multiple color indices in visible and near-infrared wavelengths. The composition of asteroids gives key information to understand their origin and evolution. However, we lack compositional information for faint asteroids due to limits of ground-based observational instruments. In the near future, the Chinese Space Survey telescope (CSST) will provide multiple colors and spectroscopic data for asteroids of apparent magnitude brighter than 25 mag and 23 mag, respectively. For the aim of analysis of the CSST spectroscopic data, we applied an algorithm using artificial neural networks (ANNs) to establish a preliminary classification model for asteroid taxonomy according to the design of the survey module of CSST. Using the SMASS II spectra and the Bus-Binzel taxonomy system, our ANN classification tool composed of 5 individual ANNs is constructed, and the accuracy of this classification system is higher than 92 %. As the first application of our ANN tool, 64 spectra of 42 asteroids obtained in 2006 and 2007 by us with the 2.16-m telescope in the Xinglong station (Observatory Code 327) of National Astronomical Observatory of China are analyzed. The predicted labels of these spectra using our ANN tool are found to be reasonable when compared to their known taxonomic labels. Considering the accuracy and stability, our ANN tool can be applied to analyse the CSST asteroid spectra in the future. © 2023, CC BY-NC-ND.

关键词： Neural networks

A comparative analysis of two peculiar long Gamma-ray bursts: GRB 230307A and GRB 211211A

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arXiv 2024年

作者： Peng, Zhao-Yang Chen, Jia-Ming Mao, Jirong College of Physics and Electronics Information Yunnan Normal University Kunming650500 China School of Physics and Astronomy Yunnan University Kunming650500 China Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100101 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

GRB 211211A is a peculiar long Gamma-ray burst (GRB) with very high brightness and short burst properties. It’s full lightcurve consists of three emission episodes, i.e. a precursor, a main burst and a extended emission. We find a recently detected long-duration GRB 230307A also includes the three consistent emission episodes. Furthermore, the two bursts have similar redshift 0.076 and 0.065, respectively. We perform a detail temporal and spectral analysis of the two GRBs to compare their temporal and spectral properties. Our analysis shows that the two bursts share great similarities for both the whole emission and the three corresponding emission phases, which are listed as follows: (1) they have near zero spectral lag, (2) they have very short minimum variability timescale (MVT), (3) they lie in the same region of in the MVT-T90, Amati relation, and hardness-T90 planes, (4) the three phases are quasi-thermal spectra, (5) both the peak energy and the low-energy index track the flux, (6) the time-resolved spectra are much wider than those of the blackbody prediced by theory model, (7) there are strong correlations between thermal flux and total flux and the correlation coefficients as well as the slopes for the corresponding stages are very consistent, (8) the photosphere emission properties are very consistent. Other investigations and observations suggest the two GRBs indeed belong to short burst with a compact star merger origin. Therefore, we think that GRB 230307A and GRB 211211A are the rare and similar GRBs and the photospheric radiation can interpret their radiation mechanisms. Copyright © 2024, The Authors. All rights reserved.

关键词： Spectrum analysis

On the External Inverse Compton Scattering off the Prompt Emission in GRB 221009A

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arXiv 2024年

作者： Dai, Cui-Yuan Zheng, Jian-He Zhao, Xiao-Hong Liu, Ruo-Yu Wang, Xiang-Yu School of Astronomy and Space Science Nanjing University Nanjing210023 China Ministry of Education Nanjing210023 China Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Science Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Science 20A Datun Road Chaoyang District Beijing100012 China

The light curve of the TeV emission in GRB 221009A displays a smooth transition from an initial rapid rise to a slower rise and eventually a decay phase. The smooth temporal profile of the TeV emission suggests that it mainly results from an external shock. The temporal overlap between the prompt KeV-MeV emission and the early TeV afterglow indicates that external inverse Compton scattering (EIC) between the prompt KeV-MeV photons and the afterglow electrons is inevitable. Since the energy density of the prompt emission is much higher than that of the afterglow during the early phase, the EIC process dominates the cooling of afterglow electrons. The EIC scattering rate is influenced by the anisotropy of the seed photon field, which depends on the radii of the internal dissipation (Rdis), where the prompt emission is produced, and that of the external shock (Rext), where the afterglow emission is produced. We investigate the EIC process for different values of Rdis/Rext. We find that, for varying Rdis/Rext, the EIC scattering rate can differ by a factor of ∼ 2. For GRB 221009A, the EIC emission is dominated during the early rising phase of the TeV afterglow. It then transitions to a phase dominated by the synchrotron self-Compton (SSC) emission as the intensity of the prompt emission decreases. Additionally, we investigate the effect of γγ absorption in the TeV afterglow caused by prompt MeV photons and find that it is insufficient to explain the early rapid rise in the TeV afterglow, even in the case of Rdis/Rext ∼ 1. Copyright © 2024, The Authors. All rights reserved.

关键词： Photons

Surface brightness-color relations for red giant branch stars using asteroseismic radii and Gaia distances (the ARD method)

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arXiv 2025年

作者： Xiong, Jianping Cheng, Qiyuan Chen, Xiaodian Li, Jiao Zhang, Xiaobin Han, Zhanwen Chen, Xuefei Yunnan Observatories Chinese Academy of Sciences 396 YangFangWang Guandu District 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 CAS Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Astronomy and Space Science University of the Chinese Academy of Sciences Beijing101408 China Department of Astronomy China West Normal University Nanchong China

Context. Surface brightness-color relations (SBCRs) are essential for estimating distances and stellar properties. Previously, SBCRs were based on a limited number of red clump giant (RC) stars, and red giant branch (RGB) stars with infrared interferometric measurements or eclipsing binaries with high-precision radii measurements, resulting in discrepancies in precision and accuracy. Recently, the large number of RGB stars with asteroseismic parameters and precise Gaia distance measurements has enabled the development of more accurate and robust SBCRs. Aims. Asteroseismic radius and Gaia distance (ARD) method has been proposed to establish the SBCRs for late-type stars. Methods. We select Kepler RGB stars with high-precision asteroseismic radii (uncertainties s-band photometric data. After applying selection criteria, we obtain 626 RGB stars to build the SBCR. Among these, 100 RGBs are used as independent validation for the distance, and the remaining samples are used to fit the SBCR. Results. First, using 526 targets with asteroseismic radii and Gaia distances, nine SBCRs are proposed based on 2MASS (J, H, Ks), APASS (Johnson-B, Johnson-V), and Gaia (G) photometry. The average rms scatter in these relations is 0.075 mag, which corresponds to an uncertainty of approximately 3.5% in distance. These relations are further validated using 100 independent samples with Gaia distances, showing no bias, with a dispersion of approximately 3%. Compared to interferometric measurements, a systematic underestimation of 2.3% was observed, and the discrepancy decreases as the angular diameter increases. Additionally, the distances of eclipsing binaries in the Large Magellanic Cloud and Small Magellanic Cloud obtained using our SBCRs are generally consistent with those measured in the literature, with a dispersion of 1% and a slight overestimation of 1% to 2.5%. Conclusions. The ARD method capitalizes on two key advantages for precise stellar distance determination: a statistically

关键词： Luminance