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arXiv 2024年

作者： Zhai, Qian Zhang, Jujia Lin, Weili Mazzali, Paolo Pian, Elena Benetti, Stefano Tomasella, Lina Liu, Jialian Li, Liping Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Department of Astronomy Xiamen University Fujian Xiamen361005 China Tsinghua University Beijing100084 China Astrophysics Research Institute Liverpool John Moores University Liverpool Science Park 146 Brownlow Hill LiverpoolL3 5RF United Kingdom Max-Planck-Institut für Astrophysik Karl-Schwarzschild Straße 1 Garching85748 Germany INAF Astrophysics and Space Science Observatory Via P. Gobetti 101 Bologna40129 Italy INAF Osservatorio Astronomico di Padova Vicolo dell’Osservatorio 5 PadovaI-35122 Italy

We present photometric and spectroscopic observations of supernova (SN) 2014C, primarily emphasizing the initial month after the explosion at approximately daily intervals. During this time, it was classified as a Type Ib SN exhibiting a notably higher peak luminosity (Lpeak ≈ 4.3 × 1042erg s−1), a faster rise to brightness (trise ≈ 11.6 d), and a more gradual dimming (∆mV15 ≈ 0.48 mag) compared to typical SNe Ib. Analysis of the velocity evolution over the first ∼ 20 days after the explosion supports the view that the absorption near 6200Å is due to high-velocity Hα in the outer layers of the ejecta, indicating the presence of a small amount of hydrogen in the envelope of progenitor before the explosion. Assuming the peak luminosity is entirely attributed to radioactive decay, we estimate that 0.14 M☉ of 56Ni was synthesized in the explosion. However, this amount of nickel could no longer maintain observed brightness approximately ten days after peak luminosity, suggesting additional energy sources beyond radioactive decay. This supplementary energy likely originates from interaction with the circumstellar medium (CSM). Consequently, the timing of the SN-CSM interaction in SN 2014C may occur much earlier than the emergence of IIn-like features during the nebular phase. © 2024, CC BY.

关键词： Supernovae

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Timing properties of the X-ray accreting pulsar RX J0440.9+4431 studied with Insight-HXMT and NICER

arXiv

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arXiv 2023年

作者： Li, P.P. Tao, L. Tuo, Y.L. Ge, M.Y. Kong, L.D. Zhang, L. Bu, Q.C. Ji, L. Qu, J.L. Zhang, S. Zhang, S.N. Huang, Y. Ma, X. Ye, W.T. Zhao, Q.C. Ma, R.C. Zhao, S.J. Hou, X. Yang, Z.X. Wang, P.J. Jia, S.M. Shui, Q.C. Guan, J. Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Uinversity of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China Institut für Astronomie und Astrophysik Kepler Center for Astro and Particle Physics Eberhard Karls Universität Sand 1 TübingenD-72076 Germany School of Physics and Astronomy Sun Yat-sen University Zhuhai519082 China 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 Physics and Optoelectronic Engineering Shandong University of Technology Zibo255000 China

RX J0440.9+4431, a Be/X-ray binary, had its brightest outburst in 2022 since its discovery, with a peak X-ray flux of 2.25 Crab (as recorded by Swift/BAT, 15-50 keV). We analyze the timing properties of this giant outburst using data from Insight-HXMT and NICER, focusing on the evolution of the pulse profile and pulse fraction. We observe that when the luminosity reached around ~3 × 1037 erg s−1, a transition from double-peaked to single-peaked pulse profiles occurred across the energy range, with the peak of the low-energy profile aligning gradually with the peak of the high-energy profile. This change indicates a transition from subcritical to supercritical accretion. Additionally, we found a concave in the pulse fraction as a function of energy around 20-30 keV throughout the entire outburst period. Compared to the low luminosity, the concave becomes weaker in high luminosities, and overall, the pulse fraction is higher. We propose that this concave could be caused by the scattering of high-energy photons by the atmosphere of a neutron star, leading to a dilution of the pulse fraction. As the accretion reaches the supercritical state, the accretion column height increases, resulting in a larger direct component of strongly beamed X-ray flux, and an elevated pulse fraction. Copyright © 2023, The Authors. All rights reserved.

关键词： Luminance

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Asteroseismic investigation on KIC 10526294 to probe convective core overshoot mixing

arXiv

引用

arXiv 2023年

作者： Zhang, Qian-Sheng Li, Yan Wu, Tao Jiang, Chen Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 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 Institute of Theoretical Physics Shanxi University Taiyuan030006 China Max-Planck-Institut für Sonnensystemforschung Justus-von-Liebig-Weg 3 GöttingenD-37077 Germany

In the overshoot mixing model with an exponentially decreasing diffusion coefficient, the initial value of the diffusion coefficient plays a crucial role. According to the turbulent convective mixing model, the characteristic length of convection in the convection zone differs from that in the overshoot region, resulting in a rapid decrease of the diffusion coefficient near the convective boundary. To investigate this quick decrease, we conducted an asteroseismic study on the intermediate-mass SPB star KIC 10526294. We generated stellar models with varied input parameters, including the overshoot parameters, and compared the resulting stellar oscillation periods with observations. To mitigate the potential issue arising from large steps in the stellar parameters and stellar age, we employed a comprehensive interpolation scheme for the stellar oscillatory frequencies, considering all stellar parameters and stellar age. Our analysis revealed that the quick decreasing of the diffusion coefficient has discernible effects on the stellar oscillations and a quick decrease with 4 magnitude orders shows the best oscillatory frequencies compared with the observations. This provides weak evidence in support of the prediction made by the turbulent convective mixing model. Furthermore, we examined the residuals of the oscillation periods and discovered a potential association between abundance anomalies in the buoyancy frequency profile and the oscillation-like patterns observed in the residuals. © 2023, CC BY.

关键词： Diffusion

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A systematic search for dual agns in merging galaxies (astro-daring): II: First results from long-slit spectroscopic observations

arXiv

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arXiv 2021年

作者： Zhang, Yang-Wei Huang, Yang Bai, Jin-Ming Liu, Xiao-Wei Wang, Jian-Guo Dong, Xiao-Bo Yunnan Observatories Chinese Academy of Sciences Yunnan Kunming650011 China South-Western Institute for Astronomy Research Yunnan University Kunming650500 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

Building a large sample of kiloparsec (kpc)-scale dual active galactic nuclei (AGNs) amongst merging galaxies is of vital importance to understand the co-evolution between host galaxies and their central super massive black holes (SMBHs). Doing so, with just such a sample, we have developed an innovative method of systematically searching and identifying dual AGNs of amongst kpc scale merging galaxies and selected 222 candidates at redshifts 6 0.25. All the selected candidates have FIRST radio detection and at least one of two cores previously revealed as AGN spectroscopically. We report the first results from A SysTematic seaRch fOr Dual Agns in meRgINg Galaxies (ASTRO-DARING), which consist of spatially resolved long-slit spectroscopic observations of 41 targets selected from our merging galaxies sample carried out between November 2014 and February 2017, using the Yunnan Faint object Spectrograph and Camera (YFOSC) mounted on the 2.4 meter telescope in Lijiang of Yunnan Observatories. Of these 16 are likely dual AGNs and 15 are newly identified. The efficiency of ASTRO-DARING is thus nearly 40 per cent. With this method, we plan to build the first even sample of more than 50 dual AGNs constructed using a consistent approach. Further analysis of the dual AGN sample shall provide vital clues for understanding the co-evolution of galaxies and SMBHs. Copyright © 2021, The Authors. All rights reserved.

关键词： Galaxies

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Back to business: SLX 1746–331 after 13 years of silence

arXiv

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arXiv 2025年

作者： Peng, Jing-Qiang Zhang, Shu Wang, Peng-Ju Zhang, Shuang-Nan Kong, Ling-Da Chen, Yu-Peng Shui, Qing-Cang Ji, Long Qu, Jin-Lu Tao, Lian Ge, Ming-Yu Ma, Rui-Can Chang, Zhi Li, Jian Li, Zhao-Sheng Yu, Zhuo-Li Yan, Zhe Zhang, Peng Xiao, Yun-Xiang Zhao, Shu-Jie Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China Institute für Astronomie und Astrophysik Kepler Center for Astro and Particle Physics Eberhard Karls Universität Sand 1 TübingenD-72076 Germany School of Physics and Astronomy Sun Yat-Sen University Zhuhai519082 China CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei230026 China School of Astronomy and Space Science University of Science and Technology of China Hefei230026 China Key Laboratory of Stars and Interstellar Medium Xiangtan University Hunan Xiangtan411105 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China College of Science China Three Gorges University Yichang443002 China Center for Astronomy and Space Sciences China Three Gorges University Yichang443002 China

The black hole candidate system SLX 1746–331 was back to business in 2023, after a long silence of roughly 13 years. An outburst was observed thoroughly by Insight-HXMT and NICER. The outburst is characterized by spectral dominance of the soft state, where the joint Insight-HXMT and NICER spectral analysis shows the temperature dependence of the disk flux follows Tin3.98, and thus suggests that the inner disk reaches to ISCO during almost the entire outburst. By assuming 0.3 LEdd for the peak flux and an inclination angle of zero degrees, the lower limit of the compact object hosted in this system is estimated as 3.28±2.14M☉. We also look into the relation of the disk temperature and disk flux for a sample of black hole systems, and by taking the disk temperature derived in the outburst of SLX 1746–331, such a relation results in a mass estimation of 5.2 ± 4.5M☉. Finally, the spin of the compact object is constrained to larger than 0.8 with a spectral model of kerrbb. Copyright © 2025, The Authors. All rights reserved.

关键词： Black holes

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A SysTematic seaRch for dual agns in meRgINg galaxies (ASTRO-DARING) III: Results from the SDSS spectroscopic surveys

arXiv

引用

arXiv 2021年

As the third installment in a series systematically searching dual active galactic nuclei (AGN) amongst merging galaxies, we present the results of 20 dual AGNs found by using the SDSS fiber spectra. To reduce the flux contamination from both the fiber aperture and seeing effects, the angular separation of two cores in our merging galaxy pairs sample is restricted at least larger than 3′′. By careful analysis of the emission lines, 20 dual AGNs are identified from 61 merging galaxies with their two cores both observed by the SDSS spectroscopic surveys. 15 of them are identified for the first time. The identification efficiency is about 32.79% (20/61), comparable to our former results (16 dual AGNs identified from 41 merging galaxies) based on the long-slit spectroscopy. Interestingly, two of the 20 dual AGNs show two prominent cores in radio images and their radio powers show they as the radio-excess AGNs. So far, 31 dual AGNs are found by our project and this is the current largest dual AGN sample, ever constructed with a consistent approach. This sample, together with more candidates from ongoing observations, is of vital importance to study the AGN physics and the coevolution between the supermassive black holes and their host galaxies. Copyright © 2021, The Authors. All rights reserved.

关键词： Galaxies

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TYC∼2990-127-1: an Algol-type SB2 binary system of subgiant and red giant with a probable ongoing mass-transfer

arXiv

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arXiv 2022年

作者： Kovalev, Mikhail Li, Zhenwei Zhang, Xiaobin Li, Jiangdan 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 Max Planck Institute for Astronomy Heidelberg D-69117 Germany Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China University of the Chinese Academy of Sciences Yuquan Road 19 Shijingshan Block Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China

We present a study of the spectroscopic binary TYC 2990-127-1 from the LAMOST survey. We use full-spectrum fitting to derive radial velocities and spectral parameters. The high mass ratio indicates that the system underwent mass transfer in the past. We compute the orbital solution and find that it is a very close sub-giant/red giant pair on circular orbit, slightly inclined to the sky-plane. Fitting of the TESS photometrical data confirms this and suggests an inclination of i ∼ 39.8◦. The light curve and spectrum around Hα show signs of irregular variability, which supports ongoing mass transfer. The binary evolution simulations suggest that the binary may experience non-conservative mass transfer with accretion efficiency 0.3, and the binary will enter into common envelope phase in the subsequent evolution. The remnant product after the ejection of common envelope may be a detached double helium white dwarf (He WD) or a merger. Copyright © 2022, The Authors. All rights reserved.

关键词： Mass transfer

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Photometric investigations on two totally eclipsing contact binaries:V342 UMa and V509 Cam

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Research in Astronomy and Astrophysics 2019年第10期19卷 75-86页

作者： Kai Li Qi-Qi Xia Jin-Zhong Liu Yu Zhang Xing Gao Shao-Ming Hu Di-Fu Guo Xu Chen Yuan Liu Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space Sciences Shandong University Weihai 264209 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi 830011 China Qilu Institute of Technology Jinan 250200 China

By analyzing two sets of complete BV Rc Ic light curves for V342 UMa and three sets of complete BV Rc Ic light curves for V509 Cam, we determined that the two systems are both W-subtype contact binaries and that V342 UMa manifests a shallow contact configuration, while V509 Cam exhibits a medium contact configuration. Given that both of them are totally eclipsing binaries, the physical parameters derived only by the photometric light curves are reliable. Meanwhile, the period changes of the two targets were analyzed based on all available eclipsing times. We discovered that V342 UMa shows long-term period decrease with a rate of-1.02(±0.54)× 10^-7 d yr^-1 and that V509 Cam displays long-term period increase with a rate of 3.96(±0.90)× 10^-8 d yr^-1. Both the conservative mass transfer and angular momentum loss via magnetic stellar winds can be used to interpret the long-term period decrease of V342 UMa. The longterm period increase of V509 Cam can be explained by mass transfer from the less massive star to the more massive one. The absolute parameters of the two binaries were estimated according to their Gaia distances and our derived photometric solution results. This method can be extended to other contact binaries without radial velocities but with reliable photometric solutions. Their evolutionary states were investigated and we found that they reveal properties that are identical to other W-subtype contact systems.

关键词： stars binaries close-stars eclipsing-stars individual (V342UMa, V509Cam)

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Atmosphere escape inferred from modelling the Hα transmission spectrum of WASP-121B

arXiv

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arXiv 2021年

作者： Yan, Dongdong Guo, Jianheng Huang, Chenliang 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 Lunar and Planetary Laboratory University of Arizona TucsonAZ85721 United States

The escaping atmospheres of hydrogen driven by stellar X-ray and extreme Ultraviolet (XUV) have been detected around some exoplanets by the excess absorption of Lyα in far ultraviolet band. In the optical band the excess absorption of Hα is also found by the ground-based instruments. However, it is not certain so far if the escape of the atmosphere driven by XUV can result in such absorption. Here we present the XUV driven hydrodynamic simulation coupled with the calculation of detailed level population and the process of radiative transfer for WASP-121b. Our fiducial model predicts a mass loss rate of ∼1.28×1012g/s for WASP-121b. Due to the high temperature and Lyα intensity predicted by the fiducial model, many hydrogen atoms are populated into the first excited state. As a consequence, the transmission spectrum of Hα simulated by our model is broadly consistent with the observation. Comparing with the absorption of Hα at different observation times, the stellar XUV emission varies in the range of 0.5-1.5 times fiducial value, which may reflect the variation of the stellar activity. Finally, we find that the supersonic regions of the planetary wind contribute a prominent portion to the absorption of Hα by comparing the equivalent width of Hα, which hints that a transonic outflow of the upper atmosphere driven by XUV irradiation of the host star can be detected by the ground-based telescope and the Hα can be a good indicator of escaping atmosphere. © 2021, CC BY-NC-ND.

关键词： Hydrogen

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Mass-Ratio Distribution of Binaries From the LAMOST-MRS Survey

arXiv

引用

arXiv 2022年

作者： Li, Jiangdan Li, Jiao Liu, Chao Li, Chunqian Guo, Yanjun Wang, Luqian Chen, Xuefei Xing, Lifeng Hou, Yonghui Han, Zhanwen 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Key Lab of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China CAS Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Nanjing Institute of Astronomical Optics & Technology National Astronomical Observatories Chinese Academy of Sciences Nanjing210042 China School of Astronomy and Space Science University of Chinese Academy of Sciences China

Binary evolution leads to the formation of important objects crucial to the development of astrophysics, but the statistical properties of binary populations are still poorly understood. The LAMOST-MRS has provided a large sample of stars to study the properties of binary populations, especially for the mass ratio distributions and the binary fractions. We have devised a Peak Amplitude Ratio (PAR) approach to derive the mass ratio of a binary system based on results obtained from its spectrum. By computing a cross-correlation function (CCF), we established a relationship between the derived mass ratio and the PARs of the binary systems. By utilizing spectral observations obtained from LAMSOT DR6 DR7, we applied the PAR approach to form distributions of the derived mass ratio of the binary systems to the spectral types. We selected the mass ratio within the range of 0.6 − 1.0 for investigating the mass-ratio distribution. Through a power-law fitting, we obtained the power index γ values of −0.42 ±0.27, 0.03 ±0.12, and 2.12 ±0.19 for A-, F-, and G-type stars identified in the sample, respectively. The derived γ-values display an increasing trend toward lower primary star masses, and G-type binaries tend to be more in twins. The close binary fractions (for P 150 d and q 0.6) in our sample for A, F and G binaries are 7.6 ± 0.5%, 4.9 ± 0.2% and 3.7 ± 0.1%, respectively. Note that the PAR approach can be applied to large spectroscopic surveys of stars. Copyright © 2022, The Authors. All rights reserved.

关键词： Surveys

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