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V752 Cen - A triple-lined spectroscopic contact binary with sudden and continuous period changes

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arXiv 2019年

作者： Zhou, X. Soonthornthum, B. Qian, S.-B. Lajús, E. Fernández P.O. Box 110 Kunming650216 China National Astronomical Research Institute of Thailand 260 Moo 4 T. Donkaew A. MaerimChiangmai50180 Thailand 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 University of the Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 China Facultad de Ciencias Astronómicas y Geofísicas Universidad Nacional de La Plata Paseo del Bosque s/n La Plata Pcia. Bs. As1900 Argentina Argentina

V752 Cen is a triple-lined spectroscopic contact binary. Its multi-color light curves were obtained in the years 1971 and 2018, independently. Photometric analyses reveal that the two sets of light curves produce almost consistent results. It contains a W-subtype totally eclipsing binary, and its mass ratio and fill-out factor are q = 3.35(1) and f = 29(2) %. The absolute elements of its two component stars were determined to be M1 = 0.39(2)M☉, M2 = 1.31(7)M☉, R1 = 0.77(1)R☉, R2 = 1.30(2)R☉, L1 = 0.75(3)L☉ and L2 = 2.00(7)L☉. The period of V752 Cen is 0.37023198 day. The 0.37-d period remained constant from its first measurement in 1971 until the year 2000. However, it changed suddenly around the year 2000 and has been increasing continuously at a rate of dP/dt = +5.05 × 10−7day · year−1 since then, which can be explained by mass transfer from the less massive component star to the more massive one with a rate of dMdt2 = 2.52 × 10−7M☉/year. The period variation of V752 Cen over the 48 years in which the period has been monitored is really unusual, and is potentially related to effects from the possible presence of a nearby third star or of a pair of stars in a second binary. Copyright © 2019, The Authors. All rights reserved.

关键词： Photometry

Ring galaxies through off-center minor collisions by tuning bulge-to-disk mass ratio of progenitors

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arXiv 2018年

作者： Chen, Guangwen Wu, Xufen Kong, Xu Liu, Wen-Juan Zhao, Hong Sheng 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 Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming Yunnan650011 China School of Physics and Astronomy University of St Andrews North Haugh FifeKY16 9SS United Kingdom

Collisional ring galaxies (CRGs) are formed through off-center collisions between a target galaxy and an intruder dwarf galaxy. We study the mass distribution and kinematics of the CRGs by tuning the bulge-to-disk mass ratio (B/D) for the progenitor;i.e., the target galaxy. We find that the lifetime of the ring correlates with the initial impact velocity vertical to the disk plane (i.e., vz0). Three orbits for the collisional galaxy pair, on which clear and asymmetric rings form after collisions, are selected to perform the N-body simulations at different values of B/D for the progenitor. It is found that the ring structures are the strongest for the CRGs with small values of B/D. The Sérsic index, n, of the central remnant in the target galaxy becomes larger after collision. Moreover, the Sérsic index of a central remnant strongly correlates with the initial value of B/D for the progenitor. A bulge-less progenitor results in a late-type object in the center of the ring galaxy, whereas a bulge-dominated progenitor leads to an early-type central remnant. Progenitors with B/D ∈ [0.1, 0.3] (i.e., minor bulges) leave central remnants with n ≈ 4. These results provide a possible explanation for the formation of a recently observed CRG with an early-type central nucleus, SDSS J1634+2049. In addition, we find that the radial and azimuthal velocity profiles for a ring galaxy are more sensitive to the B/D than the initial relative velocity of the progenitor. Su. Copyright © 2018, The Authors. All rights reserved.

关键词： Galaxies

SN 2020wnt: A slow-evolving carbon-rich superluminous supernova with no O ii lines and a bumpy light curve

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arXiv 2022年

作者： Gutiérrez, C.P. Pastorello, A. Bersten, M. Benetti, S. Orellana, M. Fiore, A. Karamehmetoglu, E. Kravtsov, T. Reguitti, A. Reynolds, T.M. Valerin, G. Mazzali, P. Sullivan, M. Cai, Y.-Z. Elias-Rosa, N. Fraser, M. Hsiao, E.Y. Kankare, E. Kotak, R. Kuncarayakti, H. Li, Z. Mattila, S. Mo, J. Moran, S. Ochner, P. Shahbandeh, M. Tomasella, L. Wang, X. Yan, S. Zhang, J. Zhang, T. Stritzinger, M.D. University of Turku FI-20014 Finland Tuorla Observatory Department of Physics and Astronomy University of Turku FI-20014 Finland INAF Osservatorio Astronomico di Padova Vicolo dell'Osservatorio 5 PadovaI-35122 Italy Facultad de Ciencias Astronómicas y Geofísicas Universidad Nacional de La Plata Paseo del Bosque S/N La PlataB1900FWA Argentina CCT CONICET UNLP. Paseo del Bosque S/N La PlataB1900FWA Argentina The University of Tokyo 5-1-5 Kashiwanoha Chiba Kashiwa277-8583 Japan Universidad Nacional de Río Negro. Sede Andina Mitre 630 Bariloche8400 Argentina Argentina Fondazione Bruno Kessler Trento Italy INFN TIFPA Trento Institute for Fundamental Physics and Applications Via Sommarive 14 TrentoI-38123 Italy Department of Physics and Astronomy Aarhus University Ny Munkegade 120 Aarhus CDK-8000 Denmark Departamento de Ciencias Físicas Universidad Andrés Bello Avda. República 252 Santiago Chile Millennium Institute of Astrophysics Nuncio Monsenor Sótero Sanz 100 Providencia Santiago Chile Denmark Niels Bohr Institute University of Copenhagen Jagtvej 128 Copenhagen N2200 Denmark Department of Physics and Astronomy G. Galilei University of Padova Vicolo dell'Osservatorio 3 Padova35122 Italy Astrophysics Research Institute Liverpool John Moores University IC2 Liverpool Science Park 146 Brownlow Hill LiverpoolL3 5RF United Kingdom Max-Planck-Institut für Astrophysik Karl-Schwarzschild Str. 1 GarchingD-85748 Germany School of Physics and Astronomy University of Southampton SouthamptonSO17 1BJ United Kingdom Tsinghua University Beijing100084 China Institute of Space Sciences ICE CSIC Campus UAB Carrer de Can Magrans s/n Barcelona08193 Spain School of Physics O'Brien Centre for Science North University College Dublin Dublin Ireland Department of Physics Florida State University 77 Chieftan Way TallahasseeFL32306 United States Turku Collegium for Science Medicine and Technology University of Turku TurkuFI-20014

We present the analysis of SN 2020wnt, an unusual hydrogen-poor super-luminous supernova (SLSN-I), at a redshift of 0.032. The light curves of SN 2020wnt are characterised by an early bump lasting ∼ 5 days, followed by a bright main peak. The SN reaches a peak absolute magnitude of Mmaxr = −20.52 ± 0.03 mag at ∼ 77.5 days from explosion. This magnitude is at the lower end of the luminosity distribution of SLSNe-I, but the rise-time is one of the longest reported to date. Unlike other SLSNe-I, the spectra of SN 2020wnt do not show O ii, but strong lines of C ii and Si ii are detected. Spectroscopically, SN 2020wnt resembles the Type Ic SN 2007gr, but its evolution is significantly slower. Comparing the bolometric light curve to hydrodynamical models, we find that SN 2020wnt luminosity can be explained by radioactive powering. The progenitor of SN 2020wnt is likely a massive and extended star with a pre-SN mass of 80 Mo and a pre-SN radius of 15 Ro that experiences a very energetic explosion of 45 × 1051 erg, producing 4 Mo of 56Ni. In this framework, the first peak results from a post-shock cooling phase for an extended progenitor, and the luminous main peak is due to a large nickel production. These characteristics are compatible with the pair-instability SN scenario. We note, however, that a significant contribution of interaction with circumstellar material cannot be ruled out. Copyright © 2022, The Authors. All rights reserved.

关键词： Supernovae

Impact of plasma instability on constraint of the intergalactic magnetic field

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arXiv 2018年

作者： Yan, Dahai Zhou, Jianeng Zhang, Pengfei Zhu, Qianqian Wang, Jiancheng Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatory Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 China Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Department of General Studies Nanchang Institute of Science & Technology Nanchang330108 China

A relativistic electron-positron pair beam can be produced in the interaction of TeV photons from a blazar with the extragalactic background light (EBL). The relativistic e± pairs would loss energy through inverse-Compton scattering (ICS) photons of cosmic microwave background (CMB) or plasma instabilities. The dominant energy-loss process is under debate. Based on the assumption that the dominant energy-loss process is ICS, the resulted cascade GeV radiation is usually used to constrain the intergalactic magnetic field (IGMF). Here, we include the energy-loss due to plasma oblique instability in the calculation of cascade gamma-ray flux, and investigate the impact of the plasma instability on the constraint of IGMF. The up-to-date GeV data and archival TeV data of the blazar 1ES 0229+200 are used. The results indicate that even if the oblique instability cooling is dominating over ICS cooling, the cascade flux could be still used to constrain the IGMF. It is found that with the ratio between the cooling rates of the oblique instability and the ICS varying from 0.1, 1 to 10, the lower limit of the IGMF putted by the cascade flux and the gamma-ray data changes from 8 × 10−18 G, 5 × 10−18 G to 10−18 G. If the ratio between the two cooling rates is 30, the estimate of IGMF based on the cascade flux is invalid. Copyright © 2018, The Authors. All rights reserved.

关键词： Magnetic fields

Study of photometric phase curve with new brightness model:refining phase function system parameters of asteroid(107)Camilla

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Research in Astronomy and Astrophysics 2016年第9期16卷 117-122页

作者： Yi-Bo Wang Xiao-Bin Wang Ao Wang Yunnan Observatories Chinese Academy of SciencesKunming 650011China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China

We characterize the morphology of the photometric phase curve model of an asteroid with a three- parameter magnitude phase function H - G1 - G2 system by considering the effect of brightness variation arising from a triaxial ellipsoid representing the asteroid＇s shape. Applying this new model and a Markov Chain Monte Carlo method, we refine the photometric phase curve of asteroid （107） Camilla and obtain its absolute magnitude H = 7.026-0.054^＋0.052 mag, and phase function parameters G1=0.489-0.044^＋0.043 and G2 = 0.259-0.023^＋***, we also determine （107） Camilla＇s orientation of pole （74.1°-4.5°^＋4.3°,50.2°-5.0°^＋5.4°）. with rotational period of 4.843928-0.000001^＋0.000001 h, and axial ratios a/b ： 1.409-0.020^＋0.020 And b/c =1.249-0.060^＋0.063. Furthermore, according to the values of phase function parameters G1 and G2, we infer that asteroid （107） Camilla is an X-type asteroid.

关键词： minor planets, asteroids general phase curve -- minor planets, asteroids individual （107）Camilla -- techniques photometric

Numerical Modelling of Tertiary Tides

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arXiv 2018年

作者： Gao, Yan Correia, Alexandre C.M. Eggleton, Peter P. Han, Zhanwen Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Department of Physics University of Coimbra Coimbra3004-516 Portugal CIDMA Department of Physics University of Aveiro Aveiro3810-193 Portugal ASD Imcce Psl University Paris Observatory 77 Av. Denfert-Rochereau Paris75014 France Lawrence Livermore National Laboratory 7000 East Ave LivermoreCA94551 United States

Stellar systems consisting of multiple stars tend to undergo tidal interactions when the separations between the stars are short. While tidal phenomena have been exten-sively studied, a certain tidal effect exclusive to hierarchical triples (triples in which one component star has a much wider orbit than the others) has hardly received any attention, mainly due to its complexity and consequent resistance to being modelled. This tidal effect is the tidal perturbation of the tertiary by the inner binary, which in turn depletes orbital energy from the inner binary, causing the inner binary separa-tion to shrink. In this paper, we develop a fully numerical simulation of these "tertiary tides"by modifying established tidal models. We also provide general insight as to how close a hierarchical triple needs to be in order for such an effect to take place, and demonstrate that our simulations can effectively retrieve the orbital evolution for such systems. We conclude that tertiary tides are a significant factor in the evolution of close hierarchical triples, and strongly influence at least ∼ 1% of all multiple star systems. Copyright © 2018, The Authors. All rights reserved.

关键词： Astrophysics

Secondary-electron radiation accompanying hadronic GeV-TeV gamma-rays from supernova remnants

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arXiv 2018年

作者： Huang, Yan Li, Zhuo Wang, Wei Zhao, Xiaohong Department of Astronomy School of Physics Peking University Beijing100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China School of Physics and Technology Wuhan University Wuhan430072 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China

The synchrotron radiation from secondary electrons and positrons (SEPs) generated by hadronic interactions in the shock of supernova remnant (SNR) could be a distinct evidence of cosmic ray (CR) production in SNR shocks. Here we provide a method where the observed gamma-ray flux from SNRs, created by pion decays, is directly used to derive the SEP distribution and hence the synchrotron spectrum. We apply the method to three gamma-ray bright SNRs. In the young SNR RX J1713.7-3946, if the observed GeV-TeV gamma-rays are of hadronic origin and the magnetic field in the SNR shock is B 0.5mG, the SEPs may produce a spectral bump at 10−5 − 10−2eV, exceeding the predicted synchrotron component of the leptonic model, and a soft spectral tail at 100keV, distinct from the hard spectral slope in the leptonic model. In the middle-aged SNRs IC443 and W44, if the observed gamma-rays are of hadronic origin, the SEP synchrotron radiation with B ∼ 400 − 500µG can well account for the observed radio flux and spectral slopes, supporting the hadronic origin of gamma-rays. Future microwave to far-infrared and hard X-ray (>100keV) observations are encouraged to constraining the SEP radiation and the gamma-ray origin in SNRs. Copyright © 2018, The Authors. All rights reserved.

关键词： Gamma rays

The spin of the second-born black hole in coalescing binary black holes

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arXiv 2018年

作者： Qin, Y. Fragos, T. Meynet, G. Andrews, J. Sørensen, M. Song, H.F. Geneva Observatory University of Geneva SauvernyCH-1290 Switzerland DARK Niels Bohr Institute University of Copenhagen Copenhagen2100 Denmark Foundation for Research and Technology - Hellas IESL Voutes Heraklion71110 Greece Physics Department & Institute of Theoretical & Computational Physics University of Crete Heraklion Crete71003 Greece College of Physics Guizhou University Guiyang CityGuizhou Province550025 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011

Context. Various binary black hole formation channels have been proposed since the first gravitational event GW150914 was discovered by the Advanced Laser Interferometer Gravitational-Wave Observatory (AdLIGO). For all evolutionary channels based on the evolution of isolated binaries, the immediate progenitor of the binary black hole is a close binary system composed of a black hole and a helium star. Aims. We study the spin angular momentum evolution of the helium star in order to constrain the spin of the second-born black hole. Methods. We perform detailed stellar structure and binary evolution calculations that take into account, mass-loss, internal differential rotation, and tidal interactions between the helium star and the black hole companion, where we also calculate the strength of the tidal interactions from first principles based on the structure of the helium stars. We systematically explore the parameter space of initial binary properties, including initial black hole and helium star masses, initial rotation of the helium star as well as metallicity. Results. We argue that the spin of the first-born black hole at its birth is negligible (. 0.1), hence the second-born black hole’s spin dominates the measured effective spin, χeff, from gravitational wave events of double black hole mergers. We find that tides can be important only when orbital periods are shorter than 2 days. Upon core collapse, the helium star produces a black hole (the second-born black hole in the system) with a spin that can span the entire range from zero to maximally spinning. We show that the bimodal distribution of the spin of the second-born black hole obtained in recent papers is mainly due to oversimplifying assumptions. We find an anti-correlation between the merging timescale of the two black holes, Tmerger, and the effective spin χeff. Finally, we provide new prescriptions for the tidal coefficient E2 for both H-rich and the helium-rich stars. Conclusions. To understand the

关键词： Gravity waves

The Intermediate-Mass Black Hole Reverberation Mapping Project: First Detection of Mid-Infrared Lags in Prototypical IMBHs in NGC 4395 and POX 52

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arXiv 2025年

作者： Sun, Jingbo Guo, Hengxiao Zuo, Wenwen Lira, Paulina Gu, Minfeng Edwards, Philip G. Wang, Shu Stevens, Jamie An, Tao Barua, Samuzal Cai, Zhen-Yi Feng, Haicheng Gupta, Alok C. Ho, Luis C. Ilić, Dragana Kovačević, Andjelka B. Li, ShaSha Mezcua, Mar Popović, Luka Č. Sánchez-Sáez, Paula Sun, Mouyuan Shen, Rongfeng Vivian, U. Vince, Oliver Wang, Junxian Wu, Xuebing Yu, Zhefu Zheng, Zhenya Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China University of Chinese Academy of Sciences 19A Yuquan Road Beijing100049 China Departamento de Astronom ìa Universidad de Chile Casilla 36D Santiago Chile CSIRO Astronomy and Space Science PO Box 76 EppingNSW1710 Australia Department of Physics & Astronomy Seoul National University Seoul08826 Korea Republic of Department of Astronomy University of Science and Technology of China Anhui Hefei230026 China School of Astronomy and Space Science University of Science and Technology of China Hefei230026 China Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Yunnan Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Yunnan Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Manora Peak Nainital263001 India Department of Astronomy School of Physics Peking University Beijing100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China University of Belgrade Faculty of Mathematics Department of Astronomy Studentski trg 16 Belgrade Serbia Hamburger Sternwarte Universitat Hamburg Gojenbergsweg 112 HamburgD-21029 Germany Campus UAB Carrer de Magrans Barcelona08193 Spain Edifici RDIT Campus UPC Castelldefels Barcelona08860 Spain Astronomical Observatory Volgina 7 Belgrade11060 Serbia European Southern Observatory Karl-Schwarzschild-Str. 2 Garching85748 Germany Department of Astronomy Xiamen University Fujian Xiamen361005 China School of Physics and Astronomy Sun Yat-Sen University Zhuhai519082 China CSST Science Center for the Guangdong-Hongkong-Macau Greater Bay Area Sun Yat-Sen University Zhuhai519082 China IPAC Caltech 1200 E. California Blvd. PasadenaCA91125 United States Department of Physics and Astr

The search for robust evidence of intermediate-mass black holes (IMBHs) is crucial for understanding black hole seeding process and the formation of supermassive black holes in the early Universe. NGC 4395 and POX 52 are two prototypical IMBH hosts, both exhibiting multi-line evidence of low-mass black hole activity. Here, we report the first detection of mid-infrared (MIR) lags in response to optical variability, with measurements of 3.0+2−149 days for NGC 4395 and 35.2+14−1127 days for POX 52 at 3.4 µm, respectively, using archival optical data and observations from the Wide-field Infrared Survey Explorer (WISE). This detection provides the first reverberation evidence of low-mass black hole activity in POX 52. The time lags of these two low-mass, low-luminosity active galactic nuclei (AGNs) generally follow the extent of the Rdust − L5100 relation found in higher-mass AGNs. Based on an empirical relation between the broad-line region and dusty torus size, we constrain the black hole mass of POX 52 to log(MBH/M☉) = 5.5 ± 0.37 (systemic and statistical errors), confirming its IMBH nature. Furthermore, long-term optical continuum monitoring of POX 52 reveals a mild inter-band lag of 1 day. However, no significant intranight variability was detected during its one-night, high-cadence monitoring, which we attribute to the longer duty cycle of fast variability in POX 52 compared to that in NGC 4395. © 2025, CC BY.

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