检索结果-内蒙古大学图书馆

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

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

CENTRAL ENGINE-POWERED BRIGHT X-RAY FLARES IN SHORT GAMMA-RAY BURSTS: A HINT OF BLACK HOLE-NEUTRON STAR MERGER?

arXiv

引用

arXiv 2018年

作者： Mu, Hui-Jun Gu, Wei-Min Mao, Jirong Hou, Shu-Jin Lin, Da-Bin Liu, Tong Department of Astronomy Xiamen University XiamenFujian361005 China Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan 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 College of Physics and Electronic Engineering Nanyang Normal University Nanyang Henan473061 China Guangxi Key Laboratory for Relativistic Astrophysics Department of Physics Guangxi University Nanning530004 China

Short gamma-ray bursts may originate from the merger of double neutron stars (NS) or that of a black hole (BH) and an NS. We propose that the bright X-ray flare related to the central engine reactivity may hint a BH-NS merger, since such a merger can provide more fall-back materials and therefore a more massive accretion disk than the NS-NS merger. Based on the observed 49 short bursts with Swift/X-ray Telescope follow-up observations, we find that three bursts have bright X-ray flares, among which three flares from two bursts are probably related to the central engine reactivity. We argue that these two bursts may originate from the BH-NS merger rather than the NS-NS merger. Our suggested link between the central engine-powered bright X-ray flare and the BH-NS merger event can be checked by the future gravitational wave detections from advanced LIGO and Virgo. keywords: accretion, accretion disks — gamma-ray burst: general — X-rays: general Copyright © 2018, The Authors. All rights reserved.

关键词： Stars

来源：评论

学校读者我要写书评

暂无评论

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

arXiv

引用

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

来源：评论

学校读者我要写书评

暂无评论

On the origin of the hard X-Ray excess of high-synchrotron-peaked BL Lac object Mrk 421

arXiv

引用

arXiv 2017年

作者： Chen, Liang Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

For the first time, Kataoka & Stawarz reported a clear detection of a hard X-ray excess, above ≿20 keV, in the high-synchrotron-peaked BL Lac object Mrk 421. We find that this feature may not be produced by the low-energy part of the same electron population that produced the Fermi/LAT γ-ray. Because of that it is required that the power-law electron energy go down to γmin ≈ 19, which predicts a very strong radio emission (radio flux larger than the observed) even considering the synchrotron self-absorption effect. We investigate the possibility of this excess being produced from the spine/layer jet structure, which has been clearly detected in Mrk 421. We find that (1) similar to one-zone modeling, the spine emissions provide good modeling of the broadband spectral energy distribution, except for the hard X-ray excess;and (2) the hard X-ray excess can be well represented by the synchrotron photons (from the layer) being inverse Compton scattered by the spine electrons. Copyright © 2017, The Authors. All rights reserved.

关键词： Gamma rays

来源：评论

学校读者我要写书评

暂无评论

What determines the observational differences of blazars？

引用

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

来源：评论

学校读者我要写书评

暂无评论

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

arXiv

引用

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

来源：评论

学校读者我要写书评

暂无评论

Binary interactions and multiple stellar populations in globular clusters

引用

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

来源：评论

学校读者我要写书评

暂无评论

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

arXiv

引用

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

来源：评论

学校读者我要写书评

暂无评论

JWST NIRSpec+MIRI Observations of the nearby Type IIP supernova 2022acko

arXiv

引用

arXiv 2024年

作者： Shahbandeh, M. Ashall, C. Hoeflich, P. Baron, E. Fox, O. Mera, T. DerKacy, J. Stritzinger, M.D. Shappee, B. Law, D. Morrison, J. Pauly, T. Pierel, J. Medler, K. Andrews, J. Baade, D. Bostroem, A. Brown, P. Burns, C. Burrow, A. Cikota, A. Cross, D. Davis, S. de Jaeger, T. Do, A. Dong, Y. Dominguez, I. Galbany, L. Janzen, D. Jencson, J. Hoang, E. Hsiao, E. Karamehmetoglu, E. Khaghani, B. Krisciunas, K. Kumar, S. Lu, J. Lundquist, M. Maund, J. Mazzali, P. Morrell, N. Patat, F. Pearson, J. Pfeffer, C. Phillips, M. Rest, A. Retamal, N. Stangl, S. Shrestha, M. Stevens, C. Suntzeff, N. Telesco, C. Tucker, M. Wang, L. Yang, Y. Cai, Y.-Z. Camacho-Neves, Y. Elias-Rosa, N. Foley, R. Jha, S. Kwok, L. Larison, C. LeBaron, N. Moran, S. Rho, J. Salmaso, I. Schmidt, J. Tinyanont, S. Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218-2410 United States Department of Physics Virginia Tech BlacksburgVA24061 United States Department of Physics Florida State University 77 Chieftan Way TallahasseeFL32306 United States Planetary Science Institute 1700 East Fort Lowell Road Suite 106 TucsonAZ85719-2395 United States Hamburger Sternwarte Gojenbergsweg 112 HamburgD-21029 Germany Dept of Physics & Astronomy University of Oklahoma 440 W. Brooks Rm 100 NormanOK United States Department of Physics and Astronomy Aarhus University Ny Munkegade 120 Aarhus CDK-8000 Denmark Institute for Astronomy University of Hawai’i at Manoa 2680 Woodlawn Dr. Hawai’i HI96822 United States Astrophysics Research Institute Liverpool John Moores University United Kingdom Gemini Observatory NSF’s NOIRLab 670 North A‘ohoku Place HiloHI96720-2700 United States Karl-Schwarzschild-Str. 2 Garching b. München85748 Germany Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721-0065 United States 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 Observatories of the Carnegie Institution for Science 813 Santa Barbara Street PasadenaCA91101 United States Homer L. Dodge Department of Physics and Astronomy University of Oklahoma 440 W. Brooks Rm 100 NormanOK73019-2061 United States Gemini Observatory NSF’s NOIRLab Casilla 603 La Serena Chile Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain Private Astronomer Laboratoire de Physique Nucléaire et de Hautes Énergies Paris75005 France Department of Physics University of California 1 Shields Avenue DavisCA95616-5270 United States Universidad de Granada Granada18071 Spain BarcelonaE-08034 Spain Department of Physics and Engineering Physics University of Saskatchewan 116 Science Place SaskatoonSKS7N 5E

We present JWST spectral and photometric observations of the Type IIP supernova (SN) 2022acko at ∼50 days past explosions. These data are the first JWST spectral observations of a core-collapse SN. We identify ∼ 30 different H i features, other features associated with products produced from the CNO cycle, and s-process elements such as Sc ii, Ba ii. By combining the JWST spectra with ground-based optical and NIR spectra, we construct a full Spectral Energy Distribution from 0.4 to 25 μm and find that the JWST spectra are fully consistent with the simultaneous JWST photometry. The data lack signatures ofCO formation and we estimate a limit on the CO mass of −8M☉. We demonstrate how the CO fundamental band limits can be used to probe underlying physics during the stellar evolution, explosion, and the environment. The observations indicate little mixing between the H envelope and C/O core in the ejecta and show no evidence for dust. The data presented here set a critical baseline for future JWST observations, where possible molecular and dust formation may be seen. © 2024, CC BY.

关键词： Supernovae

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：