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arXiv 2022年

作者： Li, Zhitong Zhang, Tianmeng Wang, Xiaofeng Sai, Hanna Zhang, Jujia Chen, Juncheng Zhao, Xulin Yan, Shengyu Wang, Bo Phillips, Mark M. Hsiao, Eric Y. Morrell, Nidia Contreras, Carlos Burns, Christopher R. Ashall, Christopher Stritzinger, Maximilian Krisciunas, Kevin Prieto, Jose Zou, Hu Wang, Jiali Ma, Jun Nie, Jundan Xue, Suijian Zhou, Xu Zhou, Zhimin Xiang, Danfeng Xi, Gaobo Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China Tsinghua University Beijing100084 China Beijing Planetarium Beijing Academy of Science and Technology Beijing100044 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 Wu Zhou University Wuzhou543002 China Department of Physics Tianjin University of Technology Tianjin300384 China Carnegie Observatories Las Campanas Observatory Casilla 601 La Serena Chile Observatories of the Carnegie Institution for Science 813 Santa Barbara Street PasadenaCA91101 United States Institute for Astronomy University of Hawai'i at Manoa 2680 Woodlawn Dr. Hawai'i HI96822 United States Department of Physics and Astronomy Aarhus University Ny Munkegade 120 Aarhus CDK-8000 Denmark George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy Texas A&M University Department of Physics and Astronomy College StationTX77843 United States Department of Astrophysical Sciences Princeton University 4 Ivy Ln. Princeton NJ08544 United States

In this paper, we present photometric and spectroscopic observations of a subluminous type Ia supernova (SN Ia) 2012ij, which has an absolute B-band peak magnitude MB,max = −17.95 ± 0.15 mag. The B-band light curve exhibits a fast post-peak decline with ∆m15(B) = 1.86 ± 0.05 mag. All the R and I/i-band light curves show a weak secondary peak/shoulder feature at about 3 weeks after the peak, like some transitional subclass of SNe Ia, which could result from an incomplete merger of near-infrared (NIR) double peaks. The spectra are characterized by Ti ii and strong Si ii λ5972 absorption features that are usually seen in low-luminosity objects like SN 1999by. The NIR spectrum before maximum light reveals weak carbon absorption features, implying the existence of unburned materials. We compare the observed properties of SN 2012ij with those predicted by the sub-Chandrasekhar-mass and the Chandrasekhar-mass delayed-detonation models, and find that both optical and NIR spectral properties can be explained to some extent by these two models. By comparing the secondary maximum features in I and i bands, we suggest that SN 2012ij is a transitional object linking normal SNe Ia to typical 91bg-like ones. From the published sample of SNe Ia from the Carnegie S upernova Pro ject II (CSP-II), we estimate that the fraction of SN 2012ij-like SNe Ia is not lower than ∼ 2%. Copyright © 2022, The Authors. All rights reserved.

关键词： Supernovae

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

arXiv

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arXiv 2020年

作者： Shi, Xiang-Dong Qian, Sheng-Bang Li, Lin-Jia Na, Wei-Wei Zhou, Xiao P. O. Box 110 Kunming650216 China University of Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 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 Yuxi normal university Fenghuang Road 134# Yuxi653100 China

ASAS J174406+2446.8 was originally found as a δ Scuti-type pulsating star with the period P=0.189068 days by ASAS survey. However, the LAMOST stellar parameters reveal that it is far beyond the red edge of pulsational instability strip on the log g - T diagram of δ Scuti pulsating stars. To understand the physical properties of the variable star, we observed it by the 1.0-m Cassegrain reflecting telescope at Yunnan Observatories. Multicolor light curves in B, V, Rc and Ic bands were obtained and are analyzed by using the W-D program. It is found that this variable star is a shallow-contact binary with an EB-type light curve and an orbital period of 0.3781 days rather than a δ Scuti star. It 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, II Per and GW Tau. All of them are at a key evolutionary phase from a semi-detached configuration to a contact system predicted by the thermal relaxation oscillation theory. The linear ephemeris was corrected by using 303 new determined times of light minimum. It is detected that the O - C curve shows a sinusoidal variationthat could be explained by the light-travel-time effect via the the presence of a cool red dwarf. The present investigation reveals that some of the δ Scuti-type stars beyond the red edge of pulsating instability strip on the log g - T diagram are misclassified eclipsing binaries. To understand their structures and evolutionary states, more studies are required in the *** Codes 85A05 Copyright © 2020, The Authors. All rights reserved.

关键词： Travel time

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High-velocity feature as the indicator of the stellar population of Type Ia supernovae

arXiv

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arXiv 2019年

作者： Meng, Xiang-Cun 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 20A Datun Road Chaoyang District Beijing100012 China

Although type Ia supernovae (SNe Ia) are very useful in many astrophysical fields, their exact nature is still unclear, e.g. the progenitor and explosion models. The high-velocity features (HVFs) in optical spectra of SNe Ia could provide some meaningful information to constrain the nature of SNe Ia. Here, I show strong evidence that the SNe Ia with strong CaII infrared triple (CaII IR3) HVF around maximum brightness associate with relatively younger population than those with weak CaII IR3 HVF, e.g. the SNe Ia with strong CaII IR3 HVF tend to occur in late-type galaxy, or early-type galaxy with significant star formation. In addition, using pixel statistics I find that the SNe Ia with strong maximum-light CaII IR3 HVF show a higher degree of association with star formation index, e.g. Hα or near-UV emission, than those with weak CaII IR3 HVF. Moreover, I find that the strength of the CaII IR3 HVF is linearly dependent on the difference of the absorption-weighted velocities between CaII IR3 and SiII 635.5 nm absorption lines, which then is a good index to diagnose whether or not there is a high-velocity component in the CaII IR3 absorption feature in the spectra of SNe Ia. I finally discussed the origin of the HVFs and the constraints from our discoveries on the progenitor model of SNe Ia. Copyright © 2019, The Authors. All rights reserved.

关键词： White dwarfs

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evolution of the quiescent disk surrounding a superoutburst of the dwarf nova TW virginis

arXiv

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arXiv 2020年

作者： Dai, Zhibin Szkody, Paula Garnavich, Peter M. Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu DistrictKunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects 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 Yuquan Road Shijingshan District Beijing100049 China University of Washington SeattleWA98195 United States University of Notre Dame Notre DameIN46556 United States

Portions of the Kepler K2 Short Cadence light curve of the dwarf nova (DN) TW Vir at quiescence are investigated using light curve modeling. The light curve was separated into 24 sections, each with a data length of ∼ 0.93 d, comprising 4 sections before and 20 after a superoutburst (SO). Due to the morphological differences, the quiescent orbital modulation is classified into three types. Using a fixed disk radius and the two component stellar parameters, all 24 synthetic disk models from the sections show a consistent configuration, consisting of a disk and two hotspots: one at the vertical side of the edge of the disk and the other one on the surface of the disk. Before the SO, the disk and a ringlike surface-hotspot are suddenly enhanced, triggering a precursor and then SO. At the end of the quiescent period following the SO and before the first normal outburst, the edge-hotspot becomes hotter, while the surface-hotspot switches into a "coolspot" with a coverage of nearly one-half of the disk surface. During quiescence, the surface-hotspot is always located at the outer part of the disk with a constant radial width. A flat radial temperature distribution of the disk is found and appears flatter when approaching the outburst. Like many U Gem-type DN with orbital periods of 3-5 hr, the mass transfer rate is significantly lower than the predictions of the standard/revised models of CV evolution. Copyright © 2020, The Authors. All rights reserved.

关键词： Mass transfer

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The environmental dependence of Spitzer dusty Supernovae

arXiv

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arXiv 2023年

作者： Xiao, Lin Szalai, Tamás Galbany, Lluís Fox, Ori Hu, Lei Hu, Maokai Yang, Yi Moriya, Takashi J. Pessi, Thallis Han, Zhanwen Wang, Xiaofeng Yan, Shengyu 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 Baoding071002 China Department of Experimental Physics Institute of Physics University of Szeged Dóm tér 9 SzegedH-6720 Hungary HUN-REN–SZTE Stellar Astrophysics Research Group H-6500 BajaSzegedi út Kt. 766 Hungary Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain BarcelonaE-08034 Spain Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States McWilliams Center for Cosmology Department of Physics Carnegie Mellon University 5000 Forbes Ave PittsburghPA15213 United States Purple Mountain Observatory Chinese Academy of Sciences Nanjing210023 China Tsinghua University Beijing100084 China Department of Astronomy University of California BerkeleyCA94720-3411 United States National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Graduate Institute for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan School of Physics and Astronomy Monash University ClaytonVIC3800 Australia Instituto de Estudios Astrofísicos Facultad de Ingeniería y Ciencias Universidad Diego Portales Av. Ejército Libertador 441 Santiago Chile Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories CAS Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Beijing Planetarium Beijing Academy of Science and Technology Beijing100044 China

Thanks to the mid-infrared capability offered by Spitzer, systematic searches of dust in SNe have been carried out over the past decade. Studies have revealed the presence of a substantial amount of dust over a broad range of SN subtypes. How normal SNe present mid-IR excess at later time and turn out to be dusty SNe can be affected by several factors, such as mass-loss history and envelope structure of progenitors and their explosion environment. All these can be combined and related to their environmental properties. A systematic analysis of SNe that exploded under a dusty environment could be of critical importance to measure the properties of the dust-veiled exploding stars, and whether such an intense dust production process is associated with the local environment. In this work, we firstly use the IFS data to study the environmental properties of dusty SNe compared to those of normal ones, and analyze correlations between the environmental properties and their dust parameters. We find that dusty SNe have a larger proportion located at higher SFR regions compared to the normal types. The occurrence of dusty SNe is less dependent on metallicity, with the oxygen abundance spanning from subsolar to oversolar metallicity. We also find the host extinction of dusty SNe scatters a lot, with about 40% of dusty SN located at extremely low extinction environments, and another 30% of them with considerably high host extinction of E(B-V)>0.6 mag. Copyright © 2023, The Authors. All rights reserved.

关键词： Supernovae

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Is bremsstrahlung a possible mechanism to explain the thermal feature in the GRB 130925A X-ray afterglow?

arXiv

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arXiv 2019年

作者： Liu, Jie-Ying Mao, Jirong Yunnan Observatories Chinese Academy of Sciences KunmingYunnan Province650011 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 Kunming650011 China

It has been reported that some X-ray spectra of gamma-ray burst (GRB) afterglows cannot be fitted by a simple power law. A blackbody component is added to precisely fit the thermal feature in these spectra. Alternatively, we propose that bremsstrahlung radiation can also be one possible mechanism to explain the thermal component of the GRB X-ray afterglow. In particular, we examine the X-ray afterglow of the ultra-long GRB 130925A in this paper. By our calculation, we find that the X-ray thermal component observed by both Swift-XRT and NuSTAR can be well explained by the bremsstrahlung radiation. Our results indicate that the GRBs with the bremsstrahlung emission in the X-ray afterglow could be born in a metal-rich and dusty environment. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

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Characterizing the Gamma-ray Emission Properties of the Globular Cluster M5 with the Fermi-LAT

arXiv

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arXiv 2024年

作者： Hou, X. Zhang, W. Freire, P.C.C. Torres, D.F. Ballet, J. Smith, D.A. Johnson, T.J. Kerr, M. Cheung, C.C. Guillemot, L. Li, J. Zhang, L. Ridolfi, A. Wang, P. Li, D. Yuan, J. Wang, N. 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 Campus UAB Barcelona08193 Spain Barcelona08034 Spain Max-Planck Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany BarcelonaE-08010 Spain Université Paris Saclay Université Paris Cité CEA CNRS AIM Gif-sur-YvetteF-91191 France Laboratoire d'Astrophysique de Bordeaux Université de Bordeaux CNRS B18N allée Geoffroy Saint-Hilaire PessacF-33615 France College of Science George Mason University FairfaxVA22030 United States Naval Research Laboratory WashingtonDC20375 United States Space Science Division Naval Research Laboratory WashingtonDC20375-5352 United States Laboratoire de Physique et Chimie de l'Environnement et de l'Espace Université d'Orléans CNRS OrléansF-45071 Cedex 02 France Station de radioastronomie de Nançay Observatoire de Paris CNRS INSU NançayF-18330 France 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 National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Centre for Astrophysics and Supercomputing Swinburne University of Technology P.O. Box 218 HawthornVIC3122 Australia INAF - Osservatorio Astronomico di Cagliari Via della Scienza 5 CA SelargiusI-09047 Italy Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Beijing102206 China University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100101 China Zhijiang Lab Hangzhou311121 China Xinjiang Astronomical Observatory Chinese Academy of Sciences Xinjiang Urumqi830011 China

We analyzed the globular cluster M5 (NGC 5904) using 15 yr of gamma-ray data from the Fermi Large Area Telescope (LAT). Using rotation ephemerides generated from Arecibo and FAST radio telescope observations, we searched for gamma-ray pulsations from the seven millisecond pulsars (MSPs) identified in M5. We detected no significant pulsations from any of the individual pulsars. In addition, we searched for possible variations of the gamma-ray emission as a function of orbital phase for all six MSPs in binary systems, but we did not detect any significant modulations. The gamma-ray emission from the direction of M5 is well described by an exponentially cutoff power-law spectral model, although other models cannot be excluded. The phase-averaged emission is consistent with being steady on a time scale of a few months. We estimate the number of MSPs in M5 to be between 1 and 10, using the gamma-ray conversion efficiencies for well-characterized gamma-ray MSPs in the Third Fermi LAT of Gamma-ray Pulsars, suggesting that the sample of known MSPs in M5 is (nearly) complete, even if it is not currently possible to rule out a diffuse component of the observed gamma rays from the cluster. Copyright © 2024, The Authors. All rights reserved.

关键词： Gamma rays

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Effects of Binary Interactions on the Early-type Galaxy Chemical evolution and Gas Cooling Functiontwo

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Chinese Astronomy and Astrophysics 2018年第4期42卷 527-537页

作者： Lang, Wang Yunnan Astronomical Observatories Chinese Academy of Sciences Kunming 650011 China University of Chinese Academy of Sciences Beijing 100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing 100012 China

In the galaxy parameter fitting by means of stellar population synthesis, it is found that compared with the evolutionary population synthesis (EPS) model without binary interactions, the stellar age and metallicity of a galaxy derived from the EPS model with binary interactions are larger. But, we are still unclear how the binary interactions affect the galaxy evolution. For the early-type galaxies with the UV-excess phenomenon, there are two main-stream explanations: recent star formation (RSF) and binary interactions. In this study, we obtain the mass return rate and chemical yield for the stellar populations with and without binary interactions. In combination with the galaxy chemical evolution and photoionization models, we study the effects of binary interactions on the chemical evolution and metallicity evolution for the early-type galaxies with the UV-excess phenomenon under the two formation mechanisms. We find that the inclusion of binary interactions can raise the ejected mass, metallicity, alpha element, and accelerate the gas cooling. These can reasonably explain the conclusions made by the EPS models. Moreover, we find that the gas cooling is more efficient under the UV-excess formation mechanism by the binary interactions rather than the RSF, and the ratio of element abundance is different for the two mechanisms, which can be further used to distinguish these two mechanisms. © 2018

关键词： Abundances—galaxies evolution Galaxies ISM—galaxies

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evolution of Dipolar Mixed-mode Coupling Factor in Red Giant Stars: Impact of Buoyancy Spike

arXiv

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arXiv 2022年

作者： Jiang, Chen Cunha, Margarida Christensen-Dalsgaard, Joergen Zhang, Qiansheng S. Gizon, Laurent Max-Planck-Institut für Sonnensystemforschung Justus-von-Liebig-Weg 3 Göttingen37077 Germany Instituto de Astrofísica e Ciências do Espaço Universidade do Porto CAUP Rua das Estrelas Porto4150-762 Portugal Stellar Astrophysics Centre Department of Physics and Astronomy Aarhus University Ny Munkegade 120 Aarhus CDK-8000 Denmark 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 Institut für Astrophysik Georg-August-Universität Göttingen Friedrich-Hund-Platz 1 Göttingen37077 Germany Center for Space Science NYUAD Institute New York University Abu Dhabi Abu Dhabi United Arab Emirates

Mixed modes observed in red giants allow for investigation of the stellar interior structures. One important feature in these structures is the buoyancy spike caused by the discontinuity of the chemical gradient left behind during the first dredge-up. The buoyancy spike emerges at the base of the convective zone in low-luminosity red giants and later becomes a glitch when the g-mode cavity expands to encompass the spike. Here, we study the impact of the buoyancy spike on the dipolar mixed modes using stellar models with different properties. We find that the applicability of the asymptotic formalisms for the coupling factor, q, varies depending on the location of the evanescent zone, relative to the position of the spike. Significant deviations between the value of q inferred from fitting the oscillation frequencies and either of the formalisms proposed in the literature are found in models with a large frequency separation in the interval 5 to 15 µHz, with evanescent zones located in a transition region which may be thin or thick. However, it is still possible to reconcile q with the predictions from the asymptotic formalisms, by choosing which formalism to use according to the value of q. For stars approaching the luminosity bump, the buoyancy spike becomes a glitch and strongly affects the mode frequencies. Fitting the frequencies without accounting for the glitch leads to unphysical variations in the inferred q, but we show that this is corrected when properly accounting for the glitch in the fitting. Copyright © 2022, The Authors. All rights reserved.

关键词： Buoyancy

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Geometric phase and topological phase diagram of the one-dimensional XXZ Heisenberg spin chain in a longitudinal field

arXiv

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arXiv 2019年

作者： Liao, Yi Gong, Xiao-Bo Guo, Chu Chen, Ping-Xing Department of Physics National University of Defense Technology Changsha410073 China Interdisciplinary Center for Quantum Information National University of Defense Technology Changsha410073 China Yunnan Observatory and Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Henan Key Laboratory of Quantum Information and Cryptography SSF IEU Zhengzhou450001 China

In this paper, we determine the geometric phase for the one-dimensional XXZ Heisenberg chain with spin-1/2, the exchange couple J and the spin anisotropy parameter ∆ in a longitudinal field(LF) with the reduced field strength h. Using the Jordan-Wigner transformation and the mean-field theory based on the Wick’s theorem, a semi-analytical theory has been developed in terms of order parameters which satisfy the self-consistent equations. The values of the order parameters are numerically computed using the matrix-product-state(MPS) method. The validity of the mean-filed theory could be checked through the comparison between the self-consistent solutions and the numerical results. Finally, we draw the the topological phase diagrams in the case J 0. Copyright © 2019, The Authors. All rights reserved.

关键词： Phase diagrams

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