检索结果-内蒙古大学图书馆

arXiv 2020年

作者： Feng, Hai-Cheng Hu, Chen Li, Sha-Sha Liu, H.T. Bai, J.M. Xing, Li-Feng Wang, Wei-Yang Yang, Zi-Xu Xiao, Ming Lu, Kai-Xing Yunnan Observatories Chinese Academy of Sciences KunmingYunnan650011 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences KunmingYunnan650011 China Key Laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences 19B Yuquan Road Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for Computational Astrophysics National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Beijing100101 China

The changes of broad emission lines should be a crucial issue to understanding the physical properties of changing-look active galactic nucleus (CL-AGN). Here, we present the results of an intensive and homogeneous 6-month long reverberation mapping (RM) monitoring campaign during a low-activity state of the CL-AGN Seyfert galaxy NGC 3516. Photometric and spectroscopic monitoring was carried out during 2018–2019 with the Lijiang 2.4 m telescope. The sampling is 2 days in most nights, and the average sampling is ∼3 days. The rest frame time lags of Hα and Hβ are τHα = 7.56+4.42−2.10 days and τHβ = 7.50+2.05−0.77 days, respectively. From a RMS Hβ line dispersion of σline = 1713.3 ± 46.7 km s−1 and a virial factor of fσ = 5.5, the central black hole mass of NGC 3516 is estimated to be MBH = 2.4+0.7−0.3 × 107M☉, which is in agreement with previous estimates. The velocity-resolved delays show that the time lags increase towards negative velocity for both Hα and Hβ. The velocity-resolved RM of Hα is done for the first time. These RM results are consistent with other observations before the spectral type change, indicating a basically constant BLR structure during the changing-look process. The CL model of changes of accretion rate seems to be favored by long-term Hβ variability and RM observations of NGC 3516. Copyright © 2020, The Authors. All rights reserved.

关键词： Galaxies

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Photometric investigations on two totally eclipsing contact binaries: V342 UMa and V509 Cam

arXiv

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arXiv 2019年

作者： Li, Kai Xia, Qi-Qi Liu, Jin-Zhong Zhang, Yu Gao, Xing Hu, Shao-Ming Guo, Di-Fu Chen, Xu Liu, Yuan Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space Sciences Shandong University Weihai264209 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi830011 China Qilu Institute of Technology Jinan250200 China

By analyzing two sets of complete BV RcIc light curves of V342 UMa and three sets of complete BV RcIc light curves of V509 Cam, we determined that the two systems are both W-subtype contact binaries and that V342 UMa shows a shallow contact configuration, while V509 Cam exhibits a medium contact configuration. Since both of them are totally eclipsing binaries, the physical parameters derived only by the photometric light curves are ***, the period changes of the two targets were analyzed based on all available eclipsing times. We discovered that V342 UMa shows long-term period decrease with a rate of −1.02(±0.54) × 10−7 days/year and that V509 Cam exhibits long-term period increase with a rate of 3.96(±0.90) × 10−8 days/year. Both the conservative mass transfer and AML via magnetic stellar winds can interpret the long-term period decrease of V342 UMa. The long-term period increase of V509 Cam can be explained by mass transfer from the less massive star to the more massive one. The absolute parameters of the two binaries were estimated according to the Gaia distances and our derived photometric solution results. This method can be extended to other contact binaries without radial velocities but with reliable photometric solutions. The evolutionary states of them were discussed, we found that they reveal identical properties of other W-subtype contact systems. Copyright © 2019, The Authors. All rights reserved.

关键词： Cams

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The contact binary V344 Lacertae: Is it a triple system?

arXiv

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arXiv 2020年

作者： Liang, Liu Shengbang, Qian Kai, Li Jiajia, He Linjia, Li Ergang, Zhao Xuzhi, Li Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China University of Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 China Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space Sciences Shandong University Weihai264209 China

The V RI passbands light curves of V344 Lac were presented and analyzed by using the latest version of the W-D code. The observed spectrum reveals that V344 Lac is not an A3 type but would be a later F type star according to the yielded temperature. The results of solution show that V344 Lac is an A-subtype contact binary, with a mediate photometric mass ratio of 0.387 ± 0.003 and a mediate contact factor of 44.6 ± 3.0%. Based on the parallax given by Gaia, the parameters of the components are estimated as: M1 = 1.16 M☉, M2 = 0.45 M☉, R1 = 1.31 R☉, R2 = 0.88 R☉, L1 = 2.512 L☉, L2 = 1.057 L☉. The period investigation indicates that V344 Lac may have an eccentric orbital oscillation, with P3 = 12.4 ± 0.5 yr, A3 = 0.0020 ± 0.0002 d, and e = 0.38 ± 0.16. Analysis shows such oscillation would be caused by a magnetic activity which can be explained by the Applegate mechanism. Meanwhile, according to the value of l3 and the estimated physical parameters of V344 Lac, the mass of the third companion may be 0.79M☉. This third body could be a wide company. Copyright © 2020, The Authors. All rights reserved.

关键词： Parameter estimation

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Asteroseismology of the DOV star PG 1159-035

arXiv

引用

arXiv 2019年

作者： Chen, Y.H. Institute of Astrophysics Chuxiong Normal University Chuxiong675000 China School of Physics and Electronical Science Chuxiong Normal University Chuxiong675000 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650011 China

Grids of DOV star models are evolved by WDEC with fixed atmospheric constituent to the spectral values of XC/XHe/XO = 50/33/17. The core compositions are from white dwarf models at highest Teff evolved by MESA. The eigenfrequencies are calculated and used to fit the observed modes. Based on 264.1 hours of photometric observations on PG 1159-035, Winget et al. identified 125 individual frequencies. Costa et al. identified 198 pulsation modes for PG 1159-035 according to the WET photometric data from 1983, 1985, 1989, and 2002. Both of them derived frequency splitting values of δσl=1 ∼ 4.2µHz and δσl=2 ∼ 6.9µHz. According to the values of δσl=1 and δσl=2, 20 triplets and 9 quintuplets are selected and used to constrain the fitting models. Our optimal model has Teff = 129000K, M∗ = 0.63M☉, logg = 7.59, log(Menv/M∗) = -5.0, and σRMS = 1.97s. The values of Teff and logg are consistent with that values of Córsico et al.. The calculated modes of minimum rate of period change correspond to modes with maximum kinetic energy distributed in the envelope. The observed rates of period change with positive and negative values can also be partially reproduced. In particular, there are negative rates of period change for the calculated modes from our optimal model, which is not found in previous work. Copyright © 2019, The Authors. All rights reserved.

关键词： White dwarfs

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The amplitude of the kilohertz quasi-periodic oscillations in 4U 1636−53 in the frequency-energy space

arXiv

引用

arXiv 2019年

作者： Ribeiro, Evandro M. Méndez, Mariano de Avellar, Marcio G.B. Zhang, Guobao Karpouzas, Konstantinos Kapteyn Astronomical Institute University of Groningen P.O. BOX 800 Groningen9700 AV Netherlands Instituto Tecnológico de Aeronáutica ITA Brazil Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China

We present for the neutron-star low-mass X-ray binary 4U 1636−53, and for the first time for any source of kilohertz quasi-periodic oscillations (kHz QPOs), the two-dimensional behaviour of the fractional rms amplitude of the kHz QPOs in the parameter space defined by QPO frequency and photon energy. We find that the rms amplitude of the lower kHz QPO increases with energy up to ∼ 12 keV and then decreases at higher energies, while the rms amplitude of the upper kHz QPO either continues increasing or levels off at high energies. The rms amplitude of the lower kHz QPO increases and then decreases with frequency, peaking at ∼ 760 Hz, while the amplitude of the upper kHz QPO decreases with frequency, with a local maximum at around ∼ 770 Hz, and is consistent with becoming zero at the same QPO frequency, ∼ 1400 Hz, in all energy bands, thus constraining the neutron-star mass at MNS ≤ 1.6M , under the assumption that this QPO reflects the Keplerian frequency at the inner edge of the accretion disc. We show that the slope of the rms energy spectrum is connected to the changing properties of the kHz QPOs in different energy bands as its frequencies change. Finally, we discuss a possible mechanism responsible for the radiative properties of the kHz QPOs and, based on a model in which the QPO arises from oscillations in a Comptonising cloud of hot electrons, we show that the properties of the kHz QPOs can constrain the thermodynamic properties of the inner accretion flow. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

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Candidates of eclipsing multiples based on extraneous eclipses on binary light curves： KIC 7622486, KIC 7668648, KIC 7670485 and KIC 8938628

引用

Research in Astronomy and Astrophysics 2017年第3期17卷 1-12页

作者： Jia Zhang Sheng-Bang Qian Jian-Duo He Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China

Four candidates of eclipsing multiples, based on new extraneous eclipses found on Kepler binary light curves, are presented and studied. KIC 7622486 is a double eclipsing binary candidate with orbital periods of 2.2799960 d and 40.246503 d. The two binary systems do not eclipse each other in the line of sight, but there is mutual gravitational influence between them which leads to the small but definite eccentricity of 0.0035（0.0022） associated with the short 2.2799960 d period orbit. KIC 7668648 is a hierarchical quadruple system candidate, with two sets of solid 203 4- 5 d period extraneous eclipses and another independent set of extraneous eclipses. A clear and credible extraneous eclipse is found on the binary light curve of KIC 7670485 which makes it a triple system candidate. Two sets of extraneous eclipses with periods of about 390 d and 220 d are found on KIC 8938628 binary curves, which not only confirm the previous conclusion of the 388.5 4- 0.3 triple system, but also indicate new additional objects that make KIC 8938628 a hierarchical quadruple system candidate. The results from these four candidates will contribute to the field of eclipsing multiples.

关键词： binaries eclipsing - techniques photometric - methods observational

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Absolute physical parameters of three poorly studied detached eclipsing binaries

arXiv

引用

arXiv 2020年

作者： Yang, Daoye Y. Li, L.-F. Han, Q.-W. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China University of the Chinese Academy of Sciences Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Beijing100012 China Key Lab of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang Beijing100012 China School of Physics and Electronics Qiannan Normal University for Nationalities Duyun558000 China

The photometric and spectroscopic data for three double-lined detached eclipsing binaries were collected from the photometric and spectral surveys. The light and radial velocity curves of each binary system were simultaneously analyzed by using Wilson-Devinney (WD) code, and the absolute physical and orbital parameters of these binaries were derived. The masses of both components of ASASSN-V J063123.82+192341.9 were found to be M1 = 1.088 ± 0.016 and M2 = 0.883 ± 0.016 M☉;and those of ASAS J011416+0426.4 were determined to be M1 = 0.934 ± 0.046 and M2 = 0.754 ± 0.043M☉;those of MW Aur were derived to be M1 = 2.052 ± 0.196 and M2 = 1.939 ± 0.193 M☉. At last, the evolutionary status of these detached binaries was discussed based on their absolute parameters and the theoretical stellar models. Copyright © 2020, The Authors. All rights reserved.

关键词： Photometry

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The first Doppler imaging of the active binary prototype RS Canum Venaticorum

arXiv

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arXiv 2020年

作者： Xiang, Yue Gu, Shenghong Wolter, U. Schmitt, J.H.M.M. Collier Cameron, A. Barnes, J.R. Mittag, M. Perdelwitz, V. Kohl, S. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 University of Chinese Academy of Sciences Beijing100049 China Hamburger Sternwarte Universität Hamburg Hamburg21029 Germany School of Physics and Astronomy University of St Andrews FifeKY16 9SS United Kingdom Department of Physical Sciences Open University Walton Hall Milton KeynesMK7 6AA United Kingdom

We present the first Doppler images of the prototypical active binary star RS CVn, derived from high-resolution spectra observed in 2004,2016 and 2017, using three different telescopes and observing sites. We apply the least-squares deconvolution technique to all observed spectra to obtain high signal-to-noise line profiles, which are used to derive the surface images of the active K-type component. Our images show a complex spot pattern on the K star, distributed widely in longitude. All starspots revealed by our Doppler images are located below a latitude of about 70°. In accordance with previous light-curve modeling studies, we find no indication of a polar spot on the K star. Using Doppler images derived from two consecutive rotational cycles, we estimate a surface differential rotation rate of ΔΩ = -0.039 ± 0.003 RAD D -1and α = ΔΩ/Ωeq= -0.030 ± 0.002 for the K star. Given the limited phase coverage during those two rotations, the uncertainty of our differential rotation estimate is presumably higher. Copyright © 2020, The Authors. All rights reserved.

关键词： Doppler effect

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Photometric study for near-Earth asteroid (155140) 2005 UD

arXiv

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arXiv 2020年

作者： Huang, Jianing N. Muinonen, K. Chen, T. Wang, Jianing B. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China School of Astronomy and Space Sciences University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for Structure and Evolution of Celestial Objects CAS Kunming650216 China Department of Physics University of Helsinki Gustaf Hällströmin katu 2 P.O. Box 64 HelsinkiFI-00014 U Finland Finnish Geospatial Research Institute Geodeetinrinne 2 MasalaFI-02430 Finland Corona borealis Observatiories Ali China

The Apollo-type near-Earth asteroid (155140) 2005 UD is thought to be a member of the Phaethon-Geminid meteor stream Complex (PGC). Its basic physical parameters are important for unveiling its origin and its relationship to the other PGC members as well as to the Geminid stream. Adopting the Lommel-Seeliger ellipsoid method and H,G1,G2 phase function, we carry out spin, shape, and phase curve inversion using the photometric data of 2005 UD. The data consists of 11 new lightcurves, 3 lightcurves downloaded from the Minor Planet Center, and 166 sparse data points downloaded from the Zwicky Transient Facility database. As a result, we derive the pole solution of (285◦.8+1−5.13, −25◦.8+5−1235) in the ecliptic frame of J2000.0 with the Copyright © 2020, The Authors. All rights reserved.

关键词： Asteroids

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Sensitive Chandra coverage of a representative sample of weak-line quasars: revealing the full range of X-ray properties

arXiv

引用

arXiv 2022年

作者： Ni, Qingling Brandt, W.N. Luo, B. Garmire, G.P. Hall, P.B. Plotkin, R.M. Shemmer, O. Timlin, J.D. Vito, F. Wu, J. Yi, W. Department of Astronomy and Astrophysics 525 Davey Lab The Pennsylvania State University University ParkPA16802 United States Institute for Gravitation and the Cosmos The Pennsylvania State University University ParkPA16802 United States Institute for Astronomy University of Edinburgh Royal Observatory EdinburghEH9 3HJ United Kingdom Department of Physics The Pennsylvania State University University ParkPA16802 United States School of Astronomy and Space Science Nanjing University Nanjing Jiangsu 210093 China Key Laboratory of Modern Astronomy and Astrophysics Nanjing University Ministry of Education Jiangsu Nanjing210093 China Huntingdon Institute for X-ray Astronomy LLC 10677 Franks Road HuntingdonPA16652 United States Department of Physics & Astronomy York University 4700 Keele Street TorontoONM3J 1P3 Canada Department of Physics University of Nevada 1664 N. Virginia St RenoNV89557 United States Department of Physics University of North Texas DentonTX76203 United States Scuola Normale Superiore Piazza dei Cavalieri 7 Pisa56126 Italy Department of Astronomy Xiamen University Fujian Xiamen361005 China Yunnan Observatories Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China

We present deeper Chandra observations for weak-line quasars (WLQs) in a representative sample that previously had limited X-ray constraints, and perform X-ray photometric analyses to reveal the full range of X-ray properties of WLQs. Only 5 of the 32 WLQs included in this representative sample remain X-ray undetected after these observations, and a stacking analysis shows that these 5 have an average X-ray weakness factor of > 85. One of the WLQs in the sample that was known to have extreme X-ray variability, SDSS J1539+3954, exhibited dramatic X-ray variability again: it changed from an X-ray normal state to an X-ray weak state within ≈ 3 months in the rest frame. This short timescale for an X-ray flux variation by a factor of 9 further supports the thick disk and outflow (TDO) model proposed to explain the X-ray and multiwavelength properties of WLQs. The overall distribution of the X-ray-to-optical properties of WLQs suggests that the TDO has an average covering factor of the X-ray emitting region of ∼ 0.5, and the column density of the TDO can range from NH ∼ 1023−24 cm−2 to NH 1024 cm−2, which leads to different levels of absorption and Compton reflection (and/or scattering) among WLQs. Copyright © 2022, The Authors. All rights reserved.

关键词： Galaxies

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