检索结果-内蒙古大学图书馆

Period studies and photometric models for two EB-type binaries EU Hya and AW Vul

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2016年第2期16卷 127-134页

作者： Yuan-Gui Yang Qun Li Hua-Li Li Hai-Feng Dai School of Physics and Electronic Information/Information College Huaibei Normal UniversityHuaibei 235000China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China

New photometry for two Algol-type binaries, 0.8065 d）, was carried out using the 60-cm telescope EU Hya （P = 0.7782 d） and AW Vul （P = at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. With the updated Wilson-Devinney code, photometric el- ements were derived from the multi-color light curves. The modeled results indicate that the two systems are near-contact binaries, whose secondary components fill their Roche lobes. The fill-out factors of the primaries are fp = 81.2 （±0.2）% for EU Hya and fp --- 82.4 （±0.3）% for AW Vul. Period analysis implies that there exists a downward parabola with a light-time orbit from the （O - C） curve. This kind of periodic oscillation may be attributed to the light-time orbit effect of a third companion. The long-term period de- crease may be caused by mass and angular momentum loss. When the orbital period decreases, the fill-out factor of fp will increase. Our results indicate that the primaries will also eventually fill their Roche lobes. EU Hya and AW Vul may possibly evolve from semi-detached binaries into contact ones.

关键词： eclipsing binaries -- stars individual （EU Hya and AW Vul） -- the third companion

Fermi-detection of γ-ray Emissions from the Hot Coronae of Radio-quiet Active Galactic Nuclei

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Abdollahi, S. Ajello, M. Alves Batista, R. Baldini, L. Bartolini, C. Bastieri, D. Becerra Gonzalez, J. Bellazzini, R. Berenji, B. Bissaldi, E. Blandford, R.D. Bonino, R. Bruel, P. Buson, S. Cameron, R.A. Caraveo, P.A. Cavazzuti, E. Chiaro, G. Cibrario, N. Ciprini, S. Cristarella Orestano, P. Cutini, S. D’Ammando, F. Di Lalla, N. Dinesh, A. Di Venere, L. Domínguez, A. Fegan, S.J. Fiori, A. Franckowiak, A. Fukazawa, Y. Funk, S. Fusco, P. Gargano, F. Gasbarra, C. Gasparrini, D. Germani, S. Giglietto, N. Giliberti, M. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guiriec, S. Hashizume, M. Hays, E. Hewitt, J.W. Horan, D. Hou, Xian Karwin, C. Kayanoki, T. Kuss, M. Laviron, A. Lemoine-Goumard, M. Li, Jian Liodakis, I. Liu, Jun-Rong Longo, F. Loparco, F. Lorusso, L. Lubrano, P. Maldera, S. Marcotulli, L. Martí-Devesa, G. Mazziotta, M.N. Mereu, I. Michelson, P.F. Mirabal, N. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Morishita, T. Morselli, A. Moskalenko, I.V. Negro, M. Niwa, R. Omodei, N. Orienti, M. Orlando, E. Ormes, J.F. Paneque, D. Panzarini, G. Persic, M. Pesce-Rollins, M. Pillera, R. Porter, T.A. Principe, G. Rainò, S. Rando, R. Rani, B. Razzano, M. Reimer, A. Reimer, O. Sánchez-Conde, M. Saz Parkinson, P.M. Serini, D. Sgrò, C. Siskind, E.J. Spandre, G. Spinelli, P. Suson, D.J. Tajima, H. Thayer, J.B. Torres, D.F. Wang, Jian-Min Zhao, Zi-Hao Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Instituto de Física Teórica UAM CSIC Universidad Autónoma de Madrid MadridE-28049 Spain Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy Università degli studi di Trento via Calepina 14 Trento38122 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova Via F. Marzolo 8 PadovaI-35131 Italy Center for Space Studies and Activities "G. Colombo" University of Padova Via Venezia 15 PadovaI-35131 Italy Instituto de Astrofísica de Canarias Universidad de La Laguna Dpto. Astrofísica Tenerife La Laguna38200 Spain Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy California State University Los Angeles Department of Physics and Astronomy Los AngelesCA90032 United States Dipartimento di Fisica "M. Merlin" dell’Università e del Politecnico di Bari via Amendola 173 BariI-70126 Italy W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy Laboratoire Leprince-Ringuet CNRS IN2P3 École polytechnique Institut Polytechnique de Paris Palaiseau91120 France Institut für Theoretische Physik and Astrophysik Universität Würzburg WürzburgD-97074 Germany INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano via E. Bassini 15 MilanoI-20133 Italy Italian Space Agency Via del Politecnico snc Roma00133 Italy Istituto Nazionale di Fisica Nucleare Sezione di Roma "Tor Vergata" RomaI-00133 Italy Space Sci

Relativistic jets around supermassive black holes (SMBHs) are well-known powerful γ-ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMBHs work in γ-ray bands is still unknown despite of great observational efforts made in the last 3 decades. Considering the previous efforts, we carefully select an AGN sample composed of 37 nearby Seyfert galaxies with ultra-hard X-rays for the goals of γ-ray detections by excluding all potential contamination in this band. Adopting a stacking technique, here we report the significant γ-ray detection (TS = 30.6, or 5.2 σ) from the sample using 15-year Fermi-Large Area Telescope (LAT) observation. We find an average γ-ray luminosity of the sample as (1.5 ± 1.0) × 1040 erg s−1 at energies from 1-300 GeV. Limited by the well-known pair production from the interaction of γ-rays with low energy photons, several GeV γ-rays are found to originate from an extended corona (∼ 2.7 × 106Rg), whereas the canonical much more compact X-ray corona (∼ 10Rg) is responsible for 1 to several GeV γ-rays. The finding of the compact region lends to strong supports to the long-time theoretical expectations, but the extended corona is beyond all the existing models. One promising scenario is that the electron-positron pairs produced in the compact X-ray corona would expand as fireball, similar to that in γ-ray bursts, forming the structure of extended corona. © 2025, CC BY.

关键词： Active Galactic Nuclei

EP240801a/XRF 240801B: An X-ray Flash Detected by the Einstein Probe and Implications of its Multiband Afterglow

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Jiang, Shuai-Qing Xu, Dong van Hoof, Agnes P.C. Lei, Wei-Hua Liu, Yuan Zhou, Hao Chen, Yong Fu, Shao-Yu Yang, Jun Liu, Xing Zhu, Zi-Pei Filippenko, Alexei V. Jonker, Peter G. Pozanenko, A.S. Gao, He Wu, Xue-Feng Zhang, Bing Lamb, Gavin P. De Pasquale, Massimiliano Kobayashi, Shiho Bauer, Franz Erik Sun, Hui Pugliese, Giovanna An, Jie D’Elia, Valerio Fynbo, Johan P.U. Zheng, WeiKang Tirado, Alberto J.C. Yin, Yi-Han Iris Zou, Yuan-Chuan Deller, Adam T. Pankov, N.S. Volnova, A.A. Moskvitin, A.S. Spiridonova, O.I. Oparin, D.V. Rumyantsev, V. Burkhonov, O.A. Egamberdiyev, Sh A. Kim, V. Krugov, M. Tatarnikov, A.M. Inasaridze, R. Levan, Andrew J. Malesani, Daniele Bjørn Ravasio, Maria E. Quirola-Vásquez, Jonathan van Dalen, Joyce N.D. Sánchez-Sierras, Javi Sánchez, Daniel Mata Littlefair, Stuart P. Chacón, Jennifer A. Torres, Manuel A.P. Chrimes, Ashley A. Sarin, Nikhil Martin-Carrillo, Antonio Dhillon, Vik Yang, Yi Brink, Thomas G. Davies, Rebecca L. Yang, Sheng Aryan, Amar Chen, Ting-Wan Kong, Albert K.H. Li, Wen-Xiong Li, Rui-Zhi Mao, Jirong Pérez-García, Ignacio Fernández-García, Emilio J. Andrews, Moira Farah, Joseph Fan, Zhou Gonzalez, Estefania Padilla Howell, D. Andrew Hartmann, Dieter Hu, Jing-Wei Jakobsson, Páll Li, Cheng-Kui Ling, Zhi-Xing McCully, Curtis Newsome, Megan Schneider, Benjamin Tinyanont, Kaew Samaporn Sun, Ning-Chen Terreran, Giacomo Tang, Qing-Wen Wang, Wen-Xin Xu, Jing-Jing Yuan, Wei-Min Zhang, Bin-Bin Zhao, Hai-Sheng Zhang, Juan National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China Altay Astronomical Observatory Xinjiang836500 China Radboud University Nijmegen Department of Astrophysics IMAPP P.O. Box 9010 Nijmegen6500 GL Netherlands Department of Astronomy School of Physics Huazhong University of Science and Technology Wuhan430074 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing210023 China Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China School of Astronomy and Space Science Nanjing University Nanjing210093 China Key Laboratory of Modern Astronomy and Astrophysics [Nanjing University Ministry of Education China Department of Astronomy University of California BerkeleyCA94720-3411 United States Space Research Institute Russian Academy of Sciences Profsoyuznaya ul. 84/32 Moscow117997 Russia National Research University "Higher School of Economics" Myasnitskaya ul. 20 Moscow101000 Russia Institutskiy Pereulok 9 Dolgoprudny141701 Russia School of Physics and Astronomy Beijing Normal University Beijing100875 China Institute for Frontier in Astronomy and Astrophysics Beijing Normal University Beijing102206 China Nevada Center for Astrophysics University of Nevada Las Vegas NV89154 United States Department of Physics and Astronomy University of Nevada Las Vegas NV89154 United States Astrophysics Research Institute Liverpool John Moores University IC2 Liverpool Science Park 146 Brownlow Hill LiverpoolL3 5RF United Kingdom University of Messina MIFT Department Via F.S. D’Alcontres 31 Messina98166 Italy Instituto de Alta Investigación Universidad de Tarapacá Casilla 7D Arica Chile Anton Pannekoek Institute of Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands RomaI-00133 It

We present multiband observations and analysis of EP240801a, a low-energy, extremely soft gammaray burst (GRB) discovered on August 1, 2024 by the Einstein Probe (EP) satellite, with a weak contemporaneous signal also detected by Fermi/GBM. Optical spectroscopy of the afterglow, obtained by GTC and Keck, identified the redshift of z = 1.6734. EP240801a exhibits a burst duration of 148 s in X-rays and 22.3 s in gamma-rays, with X-rays leading by 80.61 s. Spectral lag analysis indicates the gamma-ray signal arrived 8.3 s earlier than the X-rays. Joint spectral fitting of EP/WXT and Fermi/GBM data yields an isotropic energy Eγ,iso = (5.57+0−0.5450) × 1051 erg, a peak energy Epeak = 14.90+7−4.0871 keV, a fluence ratio S(25 − 50 keV)/S(50 − 100 keV) = 1.67+0−0.7446, classifying EP240801a as an X-ray flash (XRF). The host-galaxy continuum spectrum, inferred using Prospector, was used to correct its contribution for the observed outburst optical data. Unusual early R-band behavior and EP/FXT observations suggest multiple components in the afterglow. Three models are considered: two-component jet model, forward-reverse shock model and forward-shock model with energy injection. Both three provide resonable explanations. The two-component jet model and the energy injection model imply a relatively small initial energy and velocity of the jet in the line of sight, while the forward-reverse shock model remains typical. Under the two-component jet model, EP240801a may resemble GRB 221009A (BOAT) if the bright narrow beam is viewed on-axis. Therefore, EP240801a can be interpreted as an off-beam (narrow) jet or an intrinsically weak GRB jet. Our findings provide crucial clues for uncovering the origin of XRFs. Copyright © 2025, The Authors. All rights reserved.

关键词： Gamma rays

Chemical properties of two dense cores in a planck galactic cold clump G168.72-15.48

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Tang, Mengyao Ge, J.X. Qin, Sheng-Li Liu, Tie Wu, Yuefang Kim, Kee-Tae Liu, Sheng-Yuan Zhang, Chao He, J.H. Ju, Bing-Gang Fang, Xinhe Department of Astronomy Yunnan University Key Laboratory of Astroparticle Physics of Yunnan Province Kunming650091 China Departamento de Astronomía Universidad de Chile Camino el Observatorio 1515 Las Condes Santiago Chile Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Department of Astronomy Peking University Beijing100871 China Korea Astronomy and Space Science Institute 776 Daedeokdaero Yuseong-gu Daejeon34055 Korea Republic of University of Science and Technology 217 Gajeong-ro Yuseong-gu Daejeon34113 Korea Republic of Institute of Astronomy and Astrophysics Academia Sinica 11F of Astronomy-Mathematics Building AS/NTU No. 1 Taipei10617 Taiwan Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming Yunnan Province650011 China Camino El Observatorio 1515 Las Condes Santiago Chile Departamento de Astronomía Universidad de Chile Las Condes Santiago Chile Purple Mountain Observatory Qinghai Station Delingha817000 China Department of Electronic Engineering Zhengzhou Railway Vocational & Technical College Zhengzhou451460 China

To deepen our understanding of the chemical properties of the Planck Galactic Cold Clump (PGCC) G168.72-15.48, we performed observations of nine molecular species, namely, c-C3H, H2CO, HC5N, HC7N, SO, CCH, N2H+, CH3OH, and CH3CCH, toward two dense cores in PGCC G168.72-15.48 using the Tianma Radio Telescope and Purple Mountain Observatory Telescope. We detected c-C3H, H2CO, HC5N, N2H+, CCH, and CH3OH in both G168-H1 and G168-H2 cores, whereas HC7N and CH3CCH were detected only in G168-H1 and SO was detected only in G168-H2. Mapping observations reveal that the CCH, N2H+, CH3OH, and CH3CCH emissions are well coupled with the dust emission in G168-H1. Additionally, N2H+exhibits an exceptionally weak emission in the denser and more evolved G168-H2 core, which may be attributed to the N2H+depletion. We suggest that the N2H+depletion in G168-H2 is dominated by N2depletion, rather than the destruction by CO. The local thermodynamic equilibrium calculations indicate that the carbon-chain molecules of CCH, HC5N, HC7N, and CH3CCH are more abundant in the younger G168-H1 core. We found that starless core G168-H1 may have the properties of cold dark clouds based on its abundances of carbon-chain molecules. While, the prestellar core G168-H2 exhibits lower carbon-chain molecular abundances than the general cold dark clouds. With our gas-grain astrochemical model calculations, we attribute the observed chemical differences between G168-H1 and G168-H2 to their different gas densities and different evolutionary stages. Copyright © 2019, The Authors. All rights reserved.

关键词： Molecules

The Fermi-LAT Light Curve Repository

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Abdollahi, S. Ajello, M. Baldini, L. Ballet, J. Bastieri, D. Gonzalez, J. Becerra Bellazzini, R. Berretta, A. Bissaldi, E. Bonino, R. Brill, A. Bruel, P. Burns, E. Buson, S. Cameron, R.A. Caputo, R. Caraveo, P.A. Cibrario, N. Ciprini, S. Orestano, P. Cristarella Crnogorcevic, M. Cutini, S. D’Ammando, F. De Gaetano, S. Digel, S.W. Di Lalla, N. Di Venere, L. Domínguez, A. Ramazani, V. Fallah Fegan, S.J. Ferrara, E.C. Fiori, A. Fleischhack, H. Franckowiak, A. Fukazawa, Y. Fusco, P. Gammaldi, V. Gargano, F. Garrappa, S. Gasbarra, C. Gasparrini, D. Giglietto, N. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guiriec, S. Gustafsson, M. Hays, E. Horan, D. Hou, X. Jóhannesson, G. Kerr, M. Kocevski, D. Kuss, M. Latronico, L. Li, J. Liodakis, I. Longo, F. Loparco, F. Lorusso, L. Lott, B. Lovellette, M.N. Lubrano, P. Maldera, S. Manfreda, A. Martí-Devesa, G. Mazziotta, M.N. Mereu, I. Meyer, M. Michelson, P.F. Mizuno, T. Monzani, M.E. Morselli, A. Moskalenko, I.V. Negro, M. Omodei, N. Orlando, E. Ormes, J.F. Paneque, D. Panzarini, G. Perkins, J.S. Persic, M. Pesce-Rollins, M. Pillera, R. Porter, T.A. Principe, G. Racusin, J.L. Rainò, S. Rando, R. Rani, B. Razzano, M. Razzaque, S. Reimer, A. Reimer, O. Sánchez-Conde, M. Parkinson, P.M. Saz Scargle, Jeff Scotton, L. Serini, D. Sgrò, C. Siskind, E.J. Spandre, G. Spinelli, P. Suson, D.J. Tajima, H. Thompson, D.J. Torres, D.F. Valverde, J. Venters, T. Wadiasingh, Z. Wagner, S. Wood, K. IRAP Université de Toulouse CNRS UPS CNES ToulouseF-31028 France Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Université Paris-Saclay Université Paris Cité CEA CNRS AIM Gif-sur-YvetteF-91191 Cedex France Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova Via F. Marzolo 8 PadovaI-35131 Italy Center for Space Studies and Activities "G. Colombo" University of Padova Via Venezia 15 PadovaI-35131 Italy Instituto de Astrofísica de Canarias Observatorio del Teide C/Via Lactea s/n Tenerife La LagunaE-38205 Spain Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Dipartimento di Fisica Università degli Studi di Perugia PerugiaI-06123 Italy Dipartimento di Fisica "M. Merlin" dell’Università e del Politecnico di Bari via Amendola 173 BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy NASA Postdoctoral Program Fellow United States NASA Goddard Space Flight Center GreenbeltMD20771 United States Laboratoire Leprince-Ringuet CNRS IN2P3 École polytechnique Institut Polytechnique de Paris Palaiseau91120 France Department of physics and Astronomy Louisiana State University Baton RougeLA70803 United States Institut für Theoretische Physik and Astrophysik Universität Würzburg WürzburgD-97074 Germany W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano via E. Bassi

The Fermi Large Area Telescope (LAT) light curve repository (LCR) is a publicly available, continually updated library of gamma-ray light curves of variable Fermi-LAT sources generated over multiple timescales. The Fermi-LAT LCR aims to provide publication-quality light curves binned on timescales of 3 days, 7 days, and 30 days for 1525 sources deemed variable in the source catalog of the first 10 years of Fermi-LAT observations. The repository consists of light curves generated through full likelihood analyses that model the sources and the surrounding region, providing fluxes and photon indices for each time bin. The LCR is intended as a resource for the time-domain and multi-messenger communities by allowing users to quickly search LAT data to identify correlated variability and flaring emission episodes from gamma-ray sources. We describe the sample selection and analysis employed by the LCR and provide an overview of the associated data access portal. Copyright © 2023, The Authors. All rights reserved.

关键词： Gamma rays

Accreting He-rich material onto carbon-oxygen white dwarfs until explosive carbon ignition

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2016年第10期16卷 93-98页

作者： Cheng-YuanWu Dong-Dong Liu Wei-Hong Zhou Bo Wang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beiiing 100049China Yunnan Minzu University Kunming 650031China

Type Ia supernovae （SNe Ia） play an important role in studies of cosmology and galactic chemi- cal evolution. They are believed to be thermonuclear explosions of carbon-oxygen white dwarfs （CO WDs） when their masses approach the Chandrasekar （Ch） mass limit. However, it is still not completely under- stood how a CO WD increases its mass to the Ch-mass limit in the classical single-degenerate （SD） model. In this paper, we studied the mass accretion process in the SD model to examine whether the WD can explode as an SN Ia. Employing the stellar evolution code called modules for experiments in stellar as- trophysics （MESA）, we simulated the He accretion process onto CO WDs. We found that the WD can increase its mass to the Ch-mass limit through the SD model and explosive carbon ignition finally occurs in its center, which will lead to an SN Ia explosion. Our results imply that SNe Ia can be produced from the SD model through steady helium accretion. Moreover, this work can provide initial input parameters for explosion models of SNe Ia.

关键词： stars： evolution -- binaries： close -- supernovae： general -- white dwarfs

Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismology

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Fu, J.-N. Vauclair, G. Su, J. Machado, L. Fox Colas, F. Kim, S.-L. Cang, T.Q. Li, C. Niu, H.B. Xue, H.F. Li, Y. Jiang, X.-J. Michel, R. Alvarez, M. Dolez, N. Ma, L. Esamdin, A. Liu, J.Z. Department of Astronomy Beijing Normal University Beijing100875 China Université de Toulouse UPS-OMP IRAP Toulouse France CNRS IRAP 14 av. Edouard Belin ToulouseF-31400 France Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Instituto de Astronomía Observatorio Astronómico Nacional San Pedro Mártir Universidad Nacional Autónoma de México Ensenada Baja california22860 Mexico IMCCE Observatoire de Paris UMR 8028 CNRS ParisF-75014 France Korea Astronomy and Space Science Institute Daejeon34055 Korea Republic of National Astrononomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi830011 China

An increasing number of white dwarf stars show atmospheric chemical composition polluted by heavy elements accreted from debris disk material. The existence of such debris disks strongly suggests the presence of one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption by tidal effect. The ZZ Ceti pulsator and polluted DAZ white dwarf GD 133 is a good candidate for searching for such a potential planet. We started in 2011 a photometric follow-up of its pulsations. As a result of this work in progress, we used the data gathered from 2011 to 2015 to make an asteroseismological analysis of GD 133, providing the star parameters from a best fit model with M/Mo= 0.630 ±0.002, Teff= 12400 K ±70K, log(MHe/M)= -2.00 ±0.02, log(MH/M)= -4.50 ±0.02 and determining a rotation period of ≈ 7 days. Copyright © 2019, The Authors. All rights reserved.

关键词： White dwarfs

A study in scarlet - I. Photometric properties of a sample of Intermediate Luminosity Red Transients

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Valerin, G. Pastorello, A. Reguitti, A. Benetti, S. Cai, Y.-Z. Chen, T.-W. Eappachen, D. Elias-Rosa, N. Fraser, M. Gangopadhyay, A. Hsiao, E.Y. Howell, D.A. Inserra, C. Izzo, L. Jencson, J. Kankare, E. Kotak, R. Mazzali, P.A. Misra, K. Pignata, G. Prentice, S.J. Sand, D.J. Smartt, S.J. Stritzinger, M.D. Tartaglia, L. Valenti, S. Anderson, J.P. Andrews, J.E. Amaro, R.C. Brennan, S. Bufano, F. Callis, E. Cappellaro, E. Dastidar, R. Della Valle, M. Fiore, A. Fulton, M.D. Galbany, L. Heikkilä, T. Hiramatsu, D. Karamehmetoglu, E. Kuncarayakti, H. Leloudas, G. Lundquist, M. McCully, C. Müller-Bravo, T.E. Nicholl, M. Ochner, P. Padilla Gonzalez, E. Paraskeva, E. Pellegrino, C. Reichart, D.E. Reynolds, T.M. Roy, R. Salmaso, I. Singh, M. Turatto, M. Tomasella, L. Wyatt, S. Young, D.R. INAF - Osservatorio Astronomico di Padova Vicolo dell'Osservatorio 5 PadovaI-35122 Italy INAF - Osservatorio Astronomico di Brera Via E. Bianchi 46 LC Merate23807 Italy Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Graduate Institute of Astronomy National Central University 300 Jhongda Road Jhongli32001 Taiwan SRON Netherlands Institute for Space Research Niels Bohrweg 4 Leiden2333 CA Netherlands Department of Astrophysics IMAPP Radboud University Nijmegen P.O. Box 9010 Nijmegen6500 GL Netherlands Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain School of Physics O'Brien Centre for Science North University College Dublin Belfield Dublin 4 Ireland The Oskar Klein Centre Department of Astronomy Stockholm University AlbaNova Stockholm10691 Sweden Hiroshima Astrophysical Science Center Hiroshima University Higashi-Hiroshima Japan Department of Physics Florida State University 77 Chieftan Way TallahasseeFL32306 United States Las Cumbres Observatory 6740 Cortona Dr. Suite 102 GoletaCA93117 United States Department of Physics University of California Santa BarbaraCA93106 United States School of Physics & Astronomy Cardiff University Queens Buildings The Parade CardiffCF24 3AA United Kingdom INAF Osservatorio Astronomico di Capodimonte Salita Moiariello 16 NapoliI-80131 Italy DARK Niels Bohr Institute University of Copenhagen Jagtvej 128 Copenhagen2200 Denmark Caltech Mail Code 220-6 PasadenaCA91125 United States Tuorla Observatory Department of Physics and Astronomy University of Turku Turku20014 Finland Astrophysics Research Institute Liverpool John Moores University IC2 Liverpool Science Park 146 Brownlow Hill LiverpoolL3 5RF United Kingdom Max-Planck-Institut für Astrophysik Karl-Schwarzs

Aims. We investigate the photometric characteristics of a sample of Intermediate Luminosity Red Transients (ILRTs), a class of elusive objects with peak luminosity between that of classical novae and standard supernovae. Our goal is to provide a stepping stone in the path to unveil the physical origin of such events, thanks to the analysis of the datasets collected. Methods. We present the multi-wavelength photometric follow-up of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd and AT 2019udc. Through the analysis and modelling of their spectral energy distribution and bolometric light curves we infer the physical parameters associated with these transients. Results. All four objects display a single peaked light curve which ends in a linear decline in magnitudes at late phases. A flux excess with respect to a single black body emission is detected in the infrared domain for three objects in our sample, a few months after maximum. This feature, commonly found in ILRTs, is interpreted as a sign of dust formation. Mid infrared monitoring of NGC 300 2008OT-1 761 days after maximum allows us to infer the presence of ∼10−3-10−5 Mo of dust, depending on the chemical composition and the grain size adopted. The late time decline of the bolometric light curves of the considered ILRTs is shallower than expected for 56Ni decay, hence requiring an additional powering mechanism. James Webb Space Telescope observations of AT 2019abn prove that the object has faded below its progenitor luminosity in the mid-infrared domain, five years after its peak. Together with the disappearance of NGC 300 2008OT-1 in Spitzer images seven years after its discovery, this supports the terminal explosion scenario for ILRTs. With a simple semi-analytical model we try to reproduce the observed bolometric light curves in the context of few Mo of material ejected at few 103 km s−1 and enshrouded in an optically thick circumstellar medium. © 2024, CC BY.

关键词： Giant stars

Expanded solutions of force-free electrodynamics on general Kerr black holes

学校读者我要写书评

暂无评论

arXiv 2017年

作者： Li, Huiquan Wang, Jiancheng 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

In this work, expanded solutions of force-free magnetospheres on general Kerr black holes are derived through a radial distance expansion method. From the regular conditions both at the horizon and at spatial infinity, two previously known asymptotical solutions (one of them is actually an exact solution) are identified as the only solutions that satisfy the same conditions at the two boundaries. Taking them as initial conditions at the boundaries, expanded solutions up to the first few orders are derived by solving the stream equation order by order. It is shown that our extension of the exact solution can (partially) cure the problems of the solution: it leads to magnetic domination and a mostly timelike current for restricted parameters. Copyright © 2017, The Authors. All rights reserved.

关键词： Magnetosphere