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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

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 Radio and -ray variability analysis of S5 0716+714

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arXiv 2018年

作者： Li, H.Z. Jiang, Y.G. Yi, T.F. Guo, D.F. Chen, X. Zhang, H.M. Gao, Q.G. Lu, F.W. Ren, J.Y. Physics Department Yuxi Normal University Yuxi653100 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space Sciences Shandong University Weihai264209 China Physics Department Yunan Normal University Kunming Yunnan650092 China GXU-NAOC Center for Astrophysics and Space Sciences Department of Physics Guangxi University Nanning530004 China Guangxi Key Laboratory for the Relativistic Astrophysics Nanning530004 China

We have studied the variability of S5 0716+714 at radio 15 GHz and -ray band using three different methods. A possible periodicity of P15GHz = 266.0 ± 11.5 and P = 344.0 ± 16.4 days are obtained for radio 15 GHz and -ray light curves, respectively. The variability may be related to the intrinsically emission mechanism. The difference between the variability timescales of radio 15 GHz and -ray may be due to that the emission of radio 15 GHz is produced via the synchrotron process, while the -ray is produced by both the SSC and EC processes. Copyright © 2018, The Authors. All rights reserved.

关键词： Galaxies

Final Moments II: Observational Properties and Physical Modeling of CSM-Interacting Type II Supernovae

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arXiv 2024年

作者： Jacobson-Galán, W.V. Dessart, L. Davis, K.W. Kilpatrick, C.D. Margutti, R. Foley, R.J. Chornock, R. Terreran, G. Hiramatsu, D. Newsome, M. Padilla Gonzalez, E. Pellegrino, C. Howell, D.A. Filippenko, A.V. Anderson, J.P. Angus, C.R. Auchettl, K. Bostroem, K.A. Brink, T.G. Cartier, R. Coulter, D.A. de Boer, T. Drout, M.R. Earl, N. Ertini, K. Farah, J.R. Farias, D. Gall, C. Gao, H. Gerlach, M.A. Guo, F. Haynie, A. Hosseinzadeh, G. Ibik, A.L. Jha, S.W. Jones, D.O. Langeroodi, D. LeBaron, N. Magnier, E.A. Piro, A.L. Raimundo, S.I. Rest, A. Rest, S. Michael Rich, R. Rojas-Bravo, C. Sears, H. Taggart, K. Villar, V.A. Wainscoat, R.J. Wang, X.-F. Wasserman, A.R. Yan, S. Yang, Y. Zhang, J. Zheng, W. Department of Astronomy University of California BerkeleyCA94720-3411 United States Institut d'Astrophysique de Paris CNRS-Sorbonne Université 98 bis boulevard Arago ParisF-75014 France Department of Astronomy and Astrophysics University of California Santa CruzCA95064 United States Northwestern University EvanstonIL60202 United States Department of Physics and Astronomy Northwestern University EvanstonIL60208 United States Department of Physics University of California BerkeleyCA94720-7300 United States Las Cumbres Observatory 6740 Cortona Dr. Suite 102 GoletaCA93117 United States Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138-1516 United States The NSF AI Institute for Artificial Intelligence and Fundamental Interactions United States Department of Physics University of California Santa Barbara Santa BarbaraCA93111 United States Department of Astronomy University of Virginia CharlottesvilleVA22904 United States European Southern Observatory Alonso de Córdova 3107 Casilla 19 Santiago Chile Millennium Institute of Astrophysics MAS Nuncio Monsenor Sotero Sanz 100 Off. 104 Providencia Santiago Chile DARK Niels Bohr Institute University of Copenhagen Jagtvej 128 Copenhagen2200 Denmark Astrophysics Research Centre School of Mathematics and Physics Queen's University Belfast BelfastBT7 1NN United Kingdom School of Physics The University of Melbourne VIC3010 Australia Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721-0065 United States LSST-DA Catalyst Gemini Observatory NSF's National Optical-Infrared Astronomy Research Laboratory Casilla 603 La Serena Chile Space Telescope Science Institute BaltimoreMD21218 United States Institute for Astronomy University of Hawaii 2680 Woodlawn Drive HonoluluHI96822 United States David A. Dunlap Department of Astronomy and Astrophysics University of Toronto 50 St. George Street TorontoONM5S 3H4 Canada Department of As

We present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early-time (δt 15 cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) of H i, He i/ii, C iv, and N iii/iv/v from the CSM persist on a characteristic timescale (tIIn) that marks a transition to a lower-density CSM and the emergence of Doppler-broadened features from the fast-moving SN ejecta. Our sample, the largest to date, consists of 39 SNe with early-time IIn-like features in addition to 35 "comparison" SNe with no evidence of early-time IIn-like features, all with ultraviolet observations. The total sample consists of 50 unpublished objects with a total of 474 previously unpublished spectra and 50 multiband light curves, collected primarily through the Young Supernova Experiment and Global Supernova Project collaborations. For all sample objects, we find a significant correlation between peak ultraviolet brightness and both tIIn and the rise time, as well as evidence for enhanced peak luminosities in SNe II with IIn-like features. We quantify mass-loss rates and CSM density for the sample through matching of peak multiband absolute magnitudes, rise times, tIIn and optical SN spectra with a grid of radiation hydrodynamics and non-local thermodynamic equilibrium (nLTE) radiative-transfer simulations. For our grid of models, all with the same underlying explosion, there is a trend between the duration of the electron-scattering broadened line profiles and inferred mass-loss rate: tIIn ≈ 3.8[M¤/(0.01 M☉ yr−1)] days. Copyright © 2024, The Authors. All rights reserved.

关键词： Supernovae

What determines the observational differences of blazars？

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Research in Astronomy and Astrophysics 2016年第11期16卷 61-70页

作者： Xu-Liang Fan Jin-Ming Bai Ji-Rong Mao Yunnan Observatories Chinese Academy of Sciences Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China University of Chinese Academy of Sciences Beijing 100049 China

We examine the scenario that the Doppler factor determines the observational differences of blazars. Significantly negative correlations are found between the observational synchrotron peak frequency and the Doppler factor. After correcting the Doppler boosting, the intrinsic peak frequency has a tight linear relation with the Doppler factor. It is interesting that this relation is consistent with the scenario that the black hole mass governs both the bulk Lorentz factor and the synchrotron peak frequency. In addition, the distinction between the kinetic jet powers of BL Lac objects and fiat spectrum radio quasars disappears after the boosting factor δ2 is considered. The negative correlation between the peak frequency and the observational isotropic luminosity, known as the blazar sequence, also disappears after the Doppler boosting is corrected. We also find that the correlation between the Compton dominance and the Doppler factor exists for all types of blazars. Therefore, this correlation is unsuitable for examining the external Compton emission dominance.

关键词： galaxies： jets - BL Lacertae objects： general - quasars： general - radiation mechanisms：non-thermal

Optical precursors to X-ray binary outbursts

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arXiv 2019年

作者： Russell, D.M. Bramich, D.M. Lewis, F. AlMannaei, A. Al Qaissieh, T. Al Qasim, A. Al Yazeedi, A. Baglio, M.C. Bernardini, F. Elgalad, N. Gabuya, A. Lasota, J.P. Palado, A. Roche, P. Shivkumar, H. Udrescu, S. Zhang, G. New York University Abu Dhabi Abu Dhabi United Arab Emirates Faulkes Telescope Project School of Physics and Astronomy Cardiff University Cardiff United Kingdom Astrophysics Research Institute Liverpool John Moores University Liverpool United Kingdom Al Sadeem Observatory Abu Dhabi United Arab Emirates Mullard Space Science Laboratory University College London Dorking United Kingdom INAF–Osservatorio Astronomico di Brera Merate Italy INAF–Osservatorio Astronomico di Roma Roma Italy INAF–Osservatorio Astronomico di Capodimonte Napoli Italy Paris-Sorbonne University Abu Dhabi Abu Dhabi United Arab Emirates Institut d’Astrophysique de Paris CNRS et Sorbonne Université Paris France Nicolaus Copernicus Astronomical Center Polish Academy of Sciences Warsaw Poland Kunming China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming China Center for Astronomical Mega-Science CAS Beijing China

Disc instability models predict that for X-ray binaries in quiescence, there should be a brightening of the optical flux prior to an X-ray outburst. Tracking the X-ray variations of X-ray binaries in quiescence is generally not possible, so optical monitoring provides the best means to measure the mass accretion rate variability between outbursts, and to identify the beginning stages of new outbursts. With our regular Faulkes Telescope/Las Cumbres Observatory (LCO) monitoring we are routinely detecting the optical rise of new X-ray binary outbursts before they are detected by X-ray all-sky monitors. We present examples of detections of an optical rise in X-ray binaries prior to X-ray detection. We also present initial optical monitoring of the new black hole transient MAXI J1820+070 (ASASSN-18ey) with the Faulkes, LCO telescopes and Al Sadeem Observatory in Abu Dhabi, UAE. Finally, we introduce our new real-time data analysis pipeline, the "X-ray Binary New Early Warning System (XB-NEWS)" which aims to detect and announce new X-ray binary outbursts within a day of first optical detection. This will allow us to trigger X-ray and multi-wavelength campaigns during the very early stages of outbursts, to constrain the outburst triggering mechanism. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

VARIABILITY OF LOW-IONIZATION BROAD ABSORPTION LINE QUASARS BASED ON MULTI-EPOCH SPECTRA FROM THE SLOAN DIGITAL SKY SURVEY

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arXiv 2019年

作者： Yi, W. Brandt, W.N. Hall, P.B. Vivek, M. Grier, C.J. Ak, N. Filiz Schneider, D.P. McGraw, S.M. Department of Astronomy & Astrophysics Pennsylvania State University 525 Davey Lab University ParkPA16802 United States Yunnan Observatories Kunming650216 China Department of Physics and Astronomy York University TorontoONM3J 1P3 Canada Department of Physics Pennsylvania State University University ParkPA16802 United States Institute for Gravitation and the Cosmos Pennsylvania State University University ParkPA16802 United States Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721 United States Faculty of Sciences Department of Astronomy and Space Sciences Erciyes University Kayseri38039 Turkey Astronomy and Space Sciences Observatory and Research Center Erciyes University Kayseri38039 Turkey Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China

We present absorption variability results for 134 bona fide Mg ii broad absorption line (BAL) quasars at 0.46 . z . 2.3 covering days to ∼ 10 yr in the rest frame. We use multiple-epoch spectra from the Sloan Digital Sky Survey, which has delivered the largest such BAL-variability sample ever studied. Mg ii-BAL identifications and related measurements are compiled and presented in a catalog. We find a remarkable time-dependent asymmetry in EW variation from the sample, such that weakening troughs outnumber strengthening troughs, the first report of such a phenomenon in BAL variability. Our investigations of the sample further reveal that (i) the frequency of BAL variability is significantly lower (typically by a factor of 2) than that from high-ionization BALQSO samples;(ii) Mg ii BAL absorbers tend to have relatively high optical depths and small covering factors along our line of sight;(iii) there is no significant EW-variability correlation between Mg ii troughs at different velocities in the same quasar;and (iv) the EW-variability correlation between Mg ii and Al iii BALs is significantly stronger than that between Mg ii and C iv BALs at the same velocities. These observational results can be explained by a combined transverse-motion/ionization-change scenario, where transverse motions likely dominate the strengthening BALs while ionization changes and/or other mechanisms dominate the weakening BALs. Copyright © 2019, The Authors. All rights reserved.

关键词： Ionization

Binary interactions and multiple stellar populations in globular clusters

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Proceedings of the International Astronomical Union 2017年第S316期12卷 316-319页

作者： Dengkai Jiang Zhanwen Han Lifang Li Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming Yunnan Province 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China email: dengkai@***

Globular clusters (GCs) have multiple stellar populations, which show star-to-star abundance variations and multiple sequences (or spreads) in the Hertzsprung-Russell diagrams. It is explained by multiple generations of star-formation in GCs. However, the observed evidence of ongoing star-formation was not found within any clusters. Here we present a binary interactions scenario for the formation of multiple stellar populations in GCs, where GC stars were born in a single burst of star formation, but some of them are members of binary systems. Binary interactions can produce peculiar stars, e.g. the merged stars and the accretor stars. They are more massive than normal single stars in the same evolutionary stage, and they are rapidly rotating stars at the moment of their formation. Rotationally induced mixing can cause the variations of their surface chemical composition. This results in the single-generation GCs showing abundance anomalies.

关键词： globular clusters: general binary: general stars: evolution stars: rotation

A low-mass-ratio and deep contact binary as the progenitor of the merger V1309 Sco

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Research in Astronomy and Astrophysics 2016年第4期16卷 129-132页

作者： Li-Ying Zhu Er-Gang Zhao Xiao Zhou Yunnan Observatories Chinese Academy of SciencesKunming 650011China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China University of the Chinese Academy of Sciences Beijing 100049China

Nova Sco 2008 （=V1309 Sco） is an example of a V838 Mon type eruption rather than a typical classical nova. This enigmatic object was recently shown to have resulted from the merger of two stars in a contact binary. It is the first stellar merger that was identified to be undergoing a common envelope transient. To understand the properties of its binary progenitor, the pre-outburst light curves were analyzed by using the W-D method. The photometric solution of the 2002 light curve shows that it is a deep contact binary （f = 89.5（~40.5）%） with a mass ratio of 0.094. The asymmetry of the light curve is explained by the presence of a dark spot on the more massive component. The extremely high fill-out factor suggests that the merging of the contact binary is driven by dynamical mass loss from the outer Lagrange point. However, the analysis of the 2004 light curve indicates that no solutions were obtained even at an extremely low mass ratio of q = 0.03. This suggests that the common convective envelope of the binary system disappeared and the secondary component spiraled into the envelope of the primary in 2004. Finally, the ejection of the envelope of the primary produced the outburst.

关键词： stars： binaries： close -- stars： binaries： eclipsing -- stars： individuals （V1309 Sco） -- stars：evolution -- stars： mass-loss