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Using CSST and ejecta-wind interaction in type II-P supernovae to constrain the wind-mass loss of red supergiant stars

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arXiv 2024年

作者： Luo, Jingxiao Dessart, Luc Chen, Xuefei Liu, Zhengwei Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Institut d'Astrophysique de Paris CNRS-Sorbonne Université 98 bis boulevard Arago ParisF-75014 France

The properties of H-rich, type II-plateau supernova (SN II-P) progenitors remain uncertain, and this is primarily due to the complexities associated with red supergiant (RSG) wind-mass loss. Recent studies have suggested that the interaction of the ejecta with a standard RSG wind should produce unambiguous signatures in the optical (e.g., a broad, boxy Hα profile) and in the UV (especially Ly α and Mg ii λλ 2795, 2802) a few years following the explosion. Such features are expected to be generic in all SNe II-P and can be utilized to constrain RSG winds. Here, we investigate the possibility of detecting late-time (0.3-10 years since explosion) SNe II-P in the NUV with the China Space Station Telescope (CSST). Convolving the existing model spectra of ejecta-wind interactions in SNe II-P with the transmission functions of the CSST, we calculated the associated multiband light curves, in particular, the NUV (255 nm - 317 nm) band, as well as the NUV − r color. We find that the CSST will be able to detect the NUV radiation associated with ejecta-wind interaction for hundreds SNe II-P out to a few hundred Mpc over its ten-year main sky survey. The CSST will therefore provide a sizable sample of SNe II-P with the NUV signatures of ejecta-wind interaction. This will be helpful for understanding the mass loss history of SN II-P progenitors and their origins. © 2024, CC BY-NC-SA.

关键词： Space stations

Characterizing the γ-Ray Variability of Active Galactic Nuclei with Stochastic Process Method

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arXiv 2022年

作者： Zhang, Haiyun Yan, Dahai Zhang, Li Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences Kunming650011 China

The γ-ray astronomy in time domain has been by now progressed further as the variabilities of Active Galactic Nuclei (AGNs) on different timescales have been reported a lot. We study the γ-ray variabilities of 23 jetted AGNs through applying a stochastic process method to the ∼12.7 yr long-term light curve (LC) obtained by Fermi-Large Area Telescope (Fermi-LAT). In this method, the stochastically driven damped simple harmonic oscillator (SHO) and the damped random walk (DRW) models are used to model the long-term LCs. Our results show that the long-term variabilities of 23 AGNs can be characterized well by both SHO and DRW models. However, the SHO model is restricted in the over-damped mode and the parameters are poorly constrained. The SHO power spectral densities (PSDs) are same as the typical DRW PSD. In the plot of the rest-frame timescale that corresponds to the broken frequency in the PSD versus black hole mass, the intrinsic γ-ray characteristic timescales of 23 AGNs occupy almost the same space with the optical variability timescales obtained from the accretion disk emission. This suggests a connection between the jet and the accretion disk. Same as the optical variability of AGN accretion disk, the γ-ray timescale is also consistent with the thermal timescale caused by the thermal instability in the standard accretion disk of AGN. Copyright © 2022, The Authors. All rights reserved.

关键词： Gamma rays

Observational Properties of 155 β Cephei pulsating variable stars

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arXiv 2024年

作者： Shi, Xiang-Dong Qian, Sheng-Bang Zhu, Li-Ying Li, Lin-Jia Zhao, Er-Gang Lin, Wen-Xu P.O. Box 110 Kunming650216 China Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 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 CAS Kunming650216 China

β Cephei pulsating variable (BCEP) stars are the most massive pulsating variable stars in the main sequence, exhibiting both p- and g-mode pulsations. In this study, we identified 155 BCEP stars or candidates using data from TESS and Gaia, of which 83 were first confirmed as BCEP stars. They have visual magnitudes ranging from 8 to 12 mag and effective temperatures between approximately 20,000 and 30,000 K, while the parallaxes of most targets are between 0.2 and 0.6 mas. The study indicates that these BCEP stars have pulsation periods ranging from 0.06 to 0.31 days, with amplitudes ranging from 0.1 to 55.8 mmag in the TESS band. Additionally, the number of BCEP stars increases as the pulsation amplitude decreases. These targets align with the distribution region of BCEP stars in the luminosity-period (L-P) and temperature-period (T-P) diagrams. We have updated the LP relation of BCEP stars. The Hertzsprung-Russell (H-R) diagram indicates that these targets are in the main-sequence evolutionary phase, with masses ranging from 7 to 20 M☉ and luminosities between 2800 and 71,000 L☉. They are almost in the theoretical instability region of BCEP stars but as previously reported, this region at the low-mass end (red) is not filled. The distribution of the pulsation constant indicates that the dominant pulsation periods of BCEP stars consist mainly of low-order p-mode pulsations with a high proportion of radial fundamental modes. These BCEP stars are excellent objects for enhancing our understanding of the structure and evolution of massive stars through asteroseismology. © 2024, CC BY.

关键词： Giant stars

The C/O ratio of He-accreting carbon-oxygen white dwarfs and type Ia supernovae

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Research in Astronomy and Astrophysics 2020年第1期20卷 19-26页

作者： Xiao Cui Bo Wang Cheng-Yuan Wu Xiang-Cun Meng Zhan-Wen Han Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of the Chinese Academy of Sciences Beijing 100049China

Type Ia supernovae(SNe Ia)are thermonuclear explosions of carbon-oxygen white dwarfs(CO WDs),and are believed to be excellent cosmological distance indicators due to their high luminosity and remarkable ***,there exists a diversity among SNe Ia,and a poor understanding of the diversity hampers the improvement of the accuracy of cosmological distance *** variations of the ratios of carbon to oxygen(C/O)of WDs at explosion are suggested to contribute to the *** the canonical model of SNe Ia,a CO WD accretes matter from its companion and increases its mass till the Chandrasekhar mass limit when the WD *** this work,we studied the C/O ratio for accreting CO *** the stellar evolution code MESA,we simulated the accretion of He-rich material onto CO WDs with different initial WD masses and different mass accretion *** found that the C/O ratio varies for different *** C/O ratio of He-accreting CO WDs at explosion increases with a decreasing initial WD mass or a decreasing accretion *** various C/O ratios may,therefore,contribute to the diversity of SNe Ia.

关键词： stars:evolution supernovae:general white dwarfs

Determination method of binary fractions by the integrated spectrum

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arXiv 2024年

作者： Zhang, F. Li, L. Han, Z. Wang, X. Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China

We need to resolve the individual stars for binary fraction determinations of stellar systems. Therefore, it is not possible to obtain the binary fractions for dense or distant stellar systems. We proposed a method to determine the binary fraction of a dense or distant stellar system. The method is to first determine the binary fraction variation for any two adjacent regions and then add up those binary fraction variations along the radial direction to obtain the binary fraction for a stellar system. Binary fraction variation is derived by using ten binary fraction-sensitive spectral absorption feature indices (SAFIs) and the binary fraction variation calibrations in terms of these SAFIs. Using this method, we first presented the binary fraction variations for twenty-one Galactic globular clusters (GCs). By comparisons, we find that they agree well with the binary fractions based on the main-sequence fiducial line method by previous studies. This verifies that the above mentioned method is feasible. Next, we presented the binary fraction variations of thirteen Galactic GCs. We gave the relationships between binary fraction and various parameters, and found that binary fraction is negatively correlated with NHB and NRR, binary fraction of some studies is not strongly correlated with NBS, and the number of GCs with large binary fraction is greater at extreme blue horizontal branch population ratio. At last, if we want to obtain more accurate binary fraction, we suggest that the spectroscopic and photometric observations are conducted at an appropriate area interval for a stellar system. © 2024, CC BY-NC-ND.

关键词： Stars

The Application of Machine Learning in Tidal evolution Simulation of Star-Planet Systems

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arXiv 2024年

作者： Guo, Shuaishuai Guo, Jianheng Ji, KaiFan Liu, Hui Xing, Lei Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650011 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650011 China Yunnan Key Laboratory of SolarPhysics and Space Science 650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China

With the release of a large amount of astronomical data, an increasing number of close-in hot Jupiters have been discovered. Calculating their evolutionary curves using star-planet interaction models presents a challenge. To expedite the generation of evolutionary curves for these close-in hot Jupiter systems, we utilized tidal interaction models established on MESA to create 15,745 samples of star-planet systems and 7,500 samples of stars. Additionally, we employed a neural network (Multi-Layer Perceptron - MLP) to predict the evolutionary curves of the systems, including stellar effective temperature, radius, stellar rotation period, and planetary orbital period. The median relative errors of the predicted evolutionary curves were found to be 0.15%, 0.43%, 2.61%, and 0.57%, respectively. Furthermore, the speed at which we generate evolutionary curves exceeds that of model-generated curves by more than four orders of magnitude. We also extracted features of planetary migration states and utilized lightGBM to classify the samples into 6 categories for prediction. We found that by combining three types that undergo long-term double synchronization into one label, the classifier effectively recognized these features. Apart from systems experiencing long-term double synchronization, the median relative errors of the predicted evolutionary curves were all below 4%. Our work provides an efficient method to save significant computational resources and time with minimal loss in accuracy. This research also lays the foundation for analyzing the evolutionary characteristics of systems under different migration states, aiding in the understanding of the underlying physical mechanisms of such systems. Finally, to a large extent, our approach could replace the calculations of theoretical models. Copyright © 2024, The Authors. All rights reserved.

关键词： Stars

A catalog of new slowly pulsating B-type stars

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arXiv 2024年

作者： Shi, Xiang-Dong Qian, Sheng-Bang Zhu, Li-Ying Li, Lin-Jia P.O. Box 110 Kunming650216 China Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 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 CAS Kunming650216 China

This paper reports the discovery of new slowly pulsating B-type stars. Based on the photometric, spectral, and astrometric data of TESS, LAMOST, and Gaia surveys, we have found 286 new slowly pulsating B-type stars (SPB stars) and 21 candidates. Among these, 20 are Be stars or candidates with emission line profiles. It is shown that these SPB stars have luminosities between 40 and 2850 L☉ and effective temperatures ranging from 10000K to 21000K. Their pulsation periods are from 0.14 to 6.5 days with amplitude ranges of 0.2-20 mmag in TESS band. It is indicated that these targets follow the distribution of the SPB stars in the period-luminosity (P-L) and the period-temperature (P-T) diagrams. Their positions on the H-R diagram reveal that most of these pulsators are distributed in the instability region of SPB stars, in the main-sequence evolutionary stage, and with mass ranges of 2.5-7 M☉. However, there are some targets beyond the red edge of the theoretical instability region, which should be caused by the rapid rotation reducing the measured effective temperature. The discovery of these new SPB stars increases the total number by over 60%, which are significant samples for further investigating the structure and evolution of intermediate-mass and even massive stars by asteroseismology. © 2024, CC BY.

关键词： Giant stars

New multi-color photometric investigations of solar-like contact binary V680 Per

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Research in Astronomy and Astrophysics 2020年第4期20卷 49-56页

作者： Jing-Jing Wang Jia-Jia He Song-Qing Zhao China University of Petroleum–Beijing at Karamay Karamay 834000China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China

High-precision CCD photometric observations of the contact binary V680 Per were obtained *** symmetric multi-color light curves were analyzed by using the Wilson–Devinney(2013)*** photometric solutions suggest that V680 Per is an A-type W UMa contact binary with the mass ratio of q=0.693 and a fill-out factor of f=18.84%with a small temperature difference of 101 *** on all minimum times,the O-C curve was analyzed for the first time in this study.A cyclic oscillation(A3=0.00093 d,T3=4.92 yr)superimposed on a secular decrease(d P/dt=-8.16×10-8 d yr-1)was *** continuous decrease in period is possibly a result of mass transfer from the more massive component to the less massive one,or angular momentum loss due to a magnetic stellar *** of this secular decrease,it is predicted that the degree of contact will become higher,and V680 Per will evolve into a deeper overcontact binary.

关键词： binaries:eclipsing stars:solar-type stars:individual(V680 Per)

The eccentricity enhancement effect of intermediate-mass-ratio-inspirals: dark matter and black hole mass

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Chinese Physics C 2021年第1期45卷 414-426页

作者： Meirong Tang Zhaoyi Xu Jiancheng Wang Yunnan Observatories Chinese Academy of SciencesKunming 650216China College of Physics Guizhou UniversityGuiyang550025China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100012China University of Chinese Academy of Sciences Beijing 100049China

It was found that dark matter(DM) in an intermediate-mass-ratio-inspiral(IMRI) system has a significant enhancement effect on the orbital eccentricity of a stellar massive compact object, such as a black hole(BH),which may be tested by space-based gravitational wave(GW) detectors, including LISA, Taiji, and Tianqin in future observations. In this paper, we study the enhancement effect of the eccentricity for an IMRI under different DM density profiles and center BH masses. Our results are as follows:(1) in terms of the general DM spike distribution,the enhancement of the eccentricity is basically consistent with the power-law profile, which indicates that it is reasonable to adopt the power-law profile;(2) in the presence of a DM spike, the different masses of the center BH will affect the eccentricity, which provides a new way for us to detect the BH’s mass;and(3) considering the change in the eccentricity in the presence and absence of a DM spike, we find that it is possible to distinguish DM models by measuring the eccentricity at a scale of approximately 105 GM/c2.

关键词： BH DM models IMRI DM spike eccentricity