检索结果-内蒙古大学图书馆

arXiv 2020年

作者： Jiang, Xue-Jian Greve, Thomas R. Gao, Yu Zhang, Zhi-Yu Tan, Qinghua de Grijs, Richard Ho, Luis C. Michalowski, Michal J. Currie, Malcolm J. Wilson, Christine D. Brinks, Elias Ao, Yiping Zhao, Yinghe He, Jinhua Harada, Nanase Yang, Chentao Jiao, Qian Chung, Aeree Lee, Bumhyun Smith, Matthew W.L. Liu, Daizhong Matsushita, Satoki Shi, Yong Imanishi, Masatoshi Rawlings, Mark G. Zhu, Ming Eden, David Davis, Timothy A. Li, Xiaohu Purple Mountain Observatory Key Laboratory for Radio Astronomy Chinese Academy of Sciences 10 Yuanhua Road Nanjing210033 China Department of Physics and Astronomy University College London Gower Street LondonWC1E 6BT United Kingdom Department of Astronomy Xiamen University Xiamen Fujian361005 China European Southern Observatory Karl-Schwarzschild-Str 2 GarchingD-85748 Germany Department of Physics & Astronomy Macquarie University Balaclava Road SydneyNSW2109 Australia Centre for Astronomy Astrophysics and Astrophotonics Macquarie University Balaclava Road SydneyNSW2109 Australia International Space Science Institute-Beijing Nanertiao Zhongguancun Hai Dian District Beijing100190 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Department of Astronomy School of Physics Peking University Beijing100871 China Astronomical Observatory Institute Faculty of Physics Adam Mickiewicz University ul. Sloneczna 36 Pozná n60-286 Poland RAL Space Rutherford Appleton Laboratory Harwell Campus Didcot OxfordshireOX11 0QX United Kingdom Department of Physics and Astronomy McMaster University HamiltonONL8S 4M1 Canada Centre for Astrophysics Research University of Hertfordshire College Lane HatfieldAL10 9AB United Kingdom Yunnan Observatories Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Chinese Academy of Sciences South America Center for Astronomy National Astronomical Observatories CAS Beijing100101 China Departamento de Astronomía Universidad de Chile Casilla 36-D Santiago Chile Institute of Astronomy and Astrophysics Academia Sinica 11F of Astronomy-Mathematics Building AS/NTU No.1 Sec. 4 Roosevelt Rd Taipei10617 Taiwan European Southern Observatory Alonso de Córdova 3107 Vitacura Casilla Santiago de C

To study the high-transition dense-gas tracers and their relationships to the star formation of the inner ∼ 2 kpc circumnuclear region of NGC 253, we present HCN J = 4 − 3 and HCO+J = 4 − 3 maps obtained with the James Clerk Maxwell Telescope (JCMT). With the spatially resolved data, we compute the concentration indices r90/r50 for the different tracers. HCN and HCO+ 4-3 emission features tend to be centrally concentrated, which is in contrast to the shallower distribution of CO 1-0 and the stellar component. The dense-gas fraction (fdense, traced by the velocity-integrated-intensity ratios of HCN/CO and HCO+/CO) and the ratio R31 (CO 3-2/1-0) decline towards larger galactocentric distances, but increase with higher SFR surface density. The radial variation and the large scatter of fdense and R31 imply distinct physical conditions in different regions of the galactic disc. The relationships of fdense versus Σstellar, and SFEdense versus Σstellar are explored. SFEdense increases with higher Σstellar in this galaxy, which is inconsistent with previous work that used HCN 1-0 data. This implies that existing stellar components might have different effects on the high-J HCN and HCO+ than their low-J emission. We also find that SFEdense seems to be decreasing with higher fdense which is consistent with previous works, and it suggests that the ability of the dense gas to form stars diminishes when the average density of the gas increases. This is expected in a scenario where only the regions with high-density contrast collapse and form stars. Copyright © 2020, 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

Variable stars in the open cluster NGC 2141

引用

Research in Astronomy and Astrophysics 2015年第5期15卷 733-741页

作者： Yang-Ping Luo School of Physics & Electronic Information China West Normal University Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

We report the results of a search for variable stars in the open cluster NGC 2141. Ten variable stars are detected, among which nine are new variable stars and they are classified as three short-period W UMa-type eclipsing binaries, two EA- type eclipsing binaries, one EB-type eclipsing binary, one very short-period RS CVn- type eclipsing binary, one d-type RR Lyrae variable star, and one unknown type of variable star. The membership and physical properties are discussed, based on their light curves, positions in the color magnitude diagrams, spatial locations and periods. A known EB-type eclipsing binary is also identified as a blue straggler candidate in the cluster. Furthermore, we find that all eclipsing contact binaries have prominent asymmetric eclipses and display the O＇Connell effect, which increases with a decrease in orbital periods. This suggests that the O＇Connell effect is probably related to the evolution of the orbital period in short period eclipsing binary systems.

关键词： stars binaries general -- open clusters and associations individual （NGC 2141） -- variables general

来源：评论

学校读者我要写书评

暂无评论

RW Dor: A shallow contact binary with new orbital period investigation

arXiv

引用

arXiv 2018年

作者： Sarotsakulchai, T. Qian, S.-B. Soonthornthum, B. Lajus, E. Fernandez Liu, N.-P. Zhou, X. Zhang, J. Liao, W.-P. Reichart, D.E. Haislip, J.B. Kouprianov, V.V. Poshyachinda, S. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences 19 A Yuquan Rd. Shijingshan Beijing100049 China National Astronomical Research Institute of Thailand Ministry of Science and Technology Bangkok Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Rd. Chaoyang District Beijing100012 China Facultad de Ciencias Astronómicas y Geofísicas UNLP La Plata Buenos Aires1900 Argentina Instituto de Astrofisica de La Plata CONICET UNLP La PlataProvincia de Buenos Aires Argentina Department of Physics and Astronomy University of North Carolina CB #3255 Chapel HillNC27599 United States

New CCD photometric light curves of short period (P=0.285d) eclipsing binary RW Dor are presented. The observations performed with the PROMPT-8 robotic telescope at CTIO in Chile from March 2015 to March 2017. The other eclipse timings were obtained from the 2.15-m JS telescope at CASLEO, San Juan, Argentina in December 2011. By light-curve analysis, it is found that RW Dor is a W-type shallow contact binary with a fill-out factor f ∼ 11% and high mass ratio q ∼ 1.587 (1/q = 0.63), where the hotter component is the less massive one (M1 ∼ 0.52Mo and M2 ∼ 0.82Mo). For orbital period investigation, the new fifteen eclipse times and those in previous published were compiled. Based on O-C analysis with very weak evidence suggests that a long-term period decrease with a rate of dP/dt =-9.61 × 10-9d yr-1is superimposed on a cyclic variation (A3= 0.0054 days and P3= 49.9 yrs). The long-term period decrease can be interpreted as mass transfer from the more massive component to the less massive one or combine with the angular momentum loss (AML) via magnetic braking. In addition, with the marginal contact phase, high mass ratio (1/q > 0.4) and the long-term period decrease, all suggest that RW Dor is a newly formed contact binary via a Case A mass transfer and it will evolve into a deeper normal contact binary. If the cyclic change is correct, the light-travel time effect via the presence of a cool third body will be more plausible to explain for this. Copyright © 2018, The Authors. All rights reserved.

关键词： Travel time

来源：评论

学校读者我要写书评

暂无评论

A common-envelope wind model for Type Ia supernovae (I): Binary evolution and birth rate

arXiv

引用

arXiv 2017年

作者： Meng, X. Podsiadlowski, P. 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 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy Oxford University OxfordOX1 3RH United Kingdom

The single-degenerate (SD) model is one of the principal models for the progenitors of type Ia supernovae (SNe Ia), but some of the predictions in the most widely studied version of the SD model, i.e. the optically thick wind (OTW) model, have not been confirmed by observations. Here, we propose a new version of the SD model in which a common envelope (CE) is assumed to form when the mass-transfer rate between a carbon-oxygen white dwarf (CO WD) and its companion exceeds a critical accretion rate. The WD may gradually increase its mass at the base of the CE. Due to the large nuclear luminosity for stable hydrogen burning, the CE may expand to giant dimensions and will lose mass from the surface of the CE by a CE wind (CEW). Because of the low CE density, the binary system will avoid a fast spiral-in phase and finally re-emerge from the CE phase. Our model may share the virtues of the OTW model but avoid some of its shortcomings. We performed binary stellar evolution calculations for more than 1100 close WD + MS binaries. Compared with the OTW model, the parameter space for SNe Ia from our CEW model extends to more massive companions and less massive WDs. Correspondingly, the Galactic birth rate from the CEW model is higher than that from the OTW model by ∼30%. Finally, we discuss the uncertainties of the CEW model and the differences between our CEW model and the OTW model. Copyright © 2017, The Authors. All rights reserved.

关键词： White dwarfs

来源：评论

学校读者我要写书评

暂无评论

A 34.5 day quasi-periodic oscillation in γ-ray emission from the blazar PKS 2247–131

arXiv

引用

arXiv 2018年

作者： Zhou, Jianeng Wang, Zhongxiang Chen, Liang Wiita, Paul J. Vadakkumthani, Jithesh Morrell, Nidia Zhang, Pengfei Zhang, Jujia Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China University of Chinese Academy of Sciences 19A Yuquan Road Beijing100049 China The College of New Jersey 2000 Pennington Road EwingNJ 08628-0718 United States Inter-University Centre for Astronomy and Astrophysics Pune411 007 India Las Campanas Observatory Carnegie Observatories Casilla 601 La Serena 1700000 Chile Purple Mountain Observatory Chinese Academy of Sciences 8 Yuanhua Road Nanjing210034 China 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 20A Datun Road BeijingChaoyang District100012 China

Since 2016 October, the active galaxy PKS 2247−131 has undergone a γ-ray outburst, which we studied using data obtained with the Fermi Gamma-ray Space Telescope. The emission arises from a relativistic jet in PKS 2247−131, as an optical spectrum only shows a few weak absorption lines, typical of the BL Lacertae sub-class of the blazar class of active galactic nuclei. Here we report a 34.5 day quasi-periodic oscillation (QPO) in the emission after the initial flux peak of the outburst. Compared to one-year time-scale QPOs, previously identified in blazars in Fermi energies, PKS 2247−131 exhibits the first clear case of a relatively short, month-like oscillation. We show that this QPO can be explained in terms of a helical structure in the jet, where the viewing angle to the dominant emission region in the jet undergoes periodic changes. The time scale of the QPO suggests the presence of binary supermassive black holes in PKS 2247−131. Copyright © 2018, The Authors. All rights reserved.

关键词： Absorption spectroscopy

来源：评论

学校读者我要写书评

暂无评论

A new derivation of the relationship between diffusion coefficient and entropy in classical Brownian motion by the ensemble method

arXiv

引用

arXiv 2017年

作者： Liao, Yi Gong, Xiao-Bo Department of Physics College of Science Southern University of Science and Technology Shenzhen518055 China Yunnan Observatory and Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China University of Chinese Academy of Sciences Beijing100049 China

The diffusion coefficient–a measure of dissipation, and the entropy–a measure of fluctuation are found to be intimately correlated in many physical systems. Unlike the fluctuation dissipation theorem in linear response theory, the correlation is often strongly non-linear. To understand this complex dependence, we consider the classical Brownian diffusion in this work. Under certain rational assumption, i.e. in the bi-component fluid mixture, the mass of the Brownian particle M is far greater than that of the bath molecule m, we can adopt the weakly couple limit. Only considering the first-order approximation of the mass ratio m/M, we obtain a linear motion equation in the reference frame of the observer as a Brownian particle. Based on this equivalent equation, we get the Hamiltonian at equilibrium. Finally, using canonical ensemble method, we define a new entropy that is similar to the Kolmogorov-Sinai entropy. Further, we present an analytic expression of the relationship between the diffusion coefficient D and the entropy S in the thermal equilibrium, that is to say, D = eM~ exp [S/(kB d)], where d is the dimension of the space, kB the Boltzmann constant, ~ the reduced Planck constant and e the Euler number. This kind of scaling relation has been well-known and well-tested since the similar one for single component is firstly derived by Rosenfeld with the expansion of volume ratio. Copyright © 2017, The Authors. All rights reserved.

关键词： Entropy

来源：评论

学校读者我要写书评

暂无评论

Physical parameters and orbital period variation of a newly discovered cataclysmic variable GSC 4560-02157

arXiv

引用

arXiv 2017年

作者： Han, Zhong-Tao Qian, Sheng-Bang Voloshina, Irina Metlov, Vladimir G. Zhu, Li-Ying Li, Lin-Jia P. O. Box 110 Kunming650216 Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P. O. Box 110 Kunming650216 University of Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 Sternberg Astronomical Institute Moscow State University Universitetskij prospect 13 Moscow119992

GSC 4560-02157 is a new eclipsing cataclysmic variable with an orbital period of 0.265359 days. By using the published V- and R-band data together with our observations, we discovered that the O - C curve of GSC 4560-02157 may shows a cyclic variation with the period of 3.51 years and an amplitude of 1.40 min. If this variation is caused by a light travel-time effect via the existence of a third body, its mass can be derived as M3sini' ≈ 91.08MJup, it should be a low-mass star. In addition, several physical parameters were measured. The colour of the secondary star was determined as V - R = 0.77(±0.03) which corresponds to a spectral type of K2-3. The secondary star's mass was estimated as M2 = 0.73(±0.02)Moby combing the derived V - R value around phase 0 with the assumption that it obeys the mass-luminosity relation of the main sequence stars. This mass is consistent with the mass'period relation of CV donor stars. For the white dwarf, the eclipse durations and contacts of the white dwarf yield an upper limit of the white dwarf's radius corresponding to a lower limit mass of Mi ≈ 0.501Mo. The overestimated radius and previously published spectral data indicate that the boundary layer may has a very high temperature. Copyright © 2017, The Authors. All rights reserved.

关键词： White dwarfs

来源：评论

学校读者我要写书评

暂无评论

SN 2016X: A type ii-p supernova with a signature of shock breakout from explosion of a massive red supergiant

arXiv

引用

arXiv 2018年

作者： Huang, F. Wang, X.-F. Hosseinzadeh, G. Brown, P.J. Mo, J. Zhang, J.-J. Zhang, K.-C. Zhang, T.-M. Howell, D.-A. Arcavi, I. McCully, C. Valenti, S. Rui, L.-M. Song, H. Xiang, D.-F. Li, W.-X. Lin, H. Wang, L.-F. Physics Department and Tsinghua Centre for Astrophysics Tsinghua University Beijing100084 China Department of Astronomy Shanghai Jiao Tong University Shanghai200240 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Department of Physics University of California Santa BarbaraCA93106-9530 United States Las Cumbres Observatory 6740 Cortona Dr. Suite 102 GoletaCA93117-5575 United States George P. and Cynthia Woods Mitchell Institute for Fundamental Physics & Astronomy Texas A&M University Department of Physics Astr Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Centre for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China Department of Physics University of California 1 Shields Avenue DavisCA95616-5270 United States

We present extensive ultraviolet (UV) and optical photometry, as well as dense optical spectroscopy for type II Plateau (IIP) supernova SN 2016X that exploded in the nearby (- 15 Mpc) spiral galaxy UGC 08041. The observations span the period from 2 to 180 days after the explosion;in particular, the Swift UV data probably captured the signature of shock breakout associated with the explosion of SN 2016X. It shows very strong UV emission during the first week after explosion, with contribution of - 20 – 30% to the bolometric luminosity (versus . 15% for normal SNe IIP). Moreover, we found that this supernova has an unusually long rise time of about 12.6 ± 0.5 days in the R band (versus - 7.0 days for typical SNe IIP). The optical light curves and spectral evolution are quite similar to the fast-declining type IIP object SN 2013ej, except that SN 2016X has a relatively brighter tail. Based on the evolution of photospheric temperature as inferred from the Swift data in the early phase, we derive that the progenitor of SN 2016X has a radius of about 930 ± 70 R. This large-size star is expected to be a red supergiant star with an initial mass of & 19 – 20 M based on the mass −− radius relation of the Galactic red supergiants, and it represents one of the most largest and massive progenitors found for SNe IIP. Copyright © 2018, The Authors. All rights reserved.

关键词： Supernovae

来源：评论

学校读者我要写书评

暂无评论

Do SN 2002cx-like and SN Ia-CSM objects share the same origin?

arXiv

引用

arXiv 2017年

作者： Meng, X. Podsiadlowski, Ph. 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 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy Oxford University OxfordOX1 3RH United Kingdom

SN 2002cx-like and SN Ia-CSM objects show similar early spectra and both belong to a young stellar population, suggesting that they could share the same progenitor origin. Adopting the framework of the common-envelope-wind (CEW) model developed in Meng & Podsiadlowski (2017), we here propose that both subclasses of SNe Ia are caused by the explosion of hybrid carbon-oxygen-neon white dwarfs (CONe WDs) in single-degenerate systems, where SNe Ia- CSM explode in systems with a massive common envelope (CE) of ∼ 1 Mo, while SN 2002cxlike events correspond to those events where most of the CE has been lost in a wind. Using binary-population-synthesis (BPS) calculations, we estimate a number ratio of SNe Ia-CSM to SN 2002cx-like objects between 1/3 and 2/3 , consistent with observational constraints, and an overall contribution from hybrid CONeWDs to the total SN Ia population that also matches the observed number from these peculiar objects. Our model predicts a statistical sequence of CSM density from SN Ia-CSM to SN 2002cx-like events and normal SNe Ia, consistent with existing radio constraints. We also find a new subclass of hybrid SNe which share the properties of Type II and Type Ia SNe, consistent with some observed SNe, which do not have a surviving companion. In some cases these could even produce SNe Ia from apparently single WDs. Copyright © 2017, The Authors. All rights reserved.

关键词： White dwarfs

来源：评论

学校读者我要写书评

暂无评论

The role of environment on the star formation history of disc galaxies

arXiv

引用

arXiv 2017年

作者： Kang, Xiaoyu Zhang, Fenghui Chang, Ruixiang 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 Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China

NGC 2403, NGC 300 and M33 are three nearby pure-disc galaxies with similar stellar mass in different environments, they are benchmarks for understanding late-type spiral galaxies in different environments. The chemical evolution and growth of their discs are investigated by using the simple chemical evolution model, in which their discs are assumed to originate and grow through the accretion of the primordial gas, and the gas outflow process is also taken into account. Through comparative study of the best-fitting model predicted star formation histories for them, we hope to derive a picture of the local environment on the evolution and star formation histories of galaxies and whether or not the isolated galaxies follow similar evolution history. Our results show that these three galaxies accumulated more than 50 percent of their stellar mass at z 25−1. The similar metallicity gradients in NGC 2403 and NGC 300 indicate that they may experience similar chemical evolutionary histories. The principal epoch of star formation on the discs of NGC 2403 and NGC 300 is earlier than that on the disc of M33, and the mean age of stellar populations along the discs of both NGC 2403 and NGC 300 is older than that of M33. Our results indicates that the evolution and star formation history of a galaxy indeed depends on its local environment, at least for galaxies with stellar mass of 109.2 M ∼ 109.7 M. Copyright © 2017, The Authors. All rights reserved.

关键词： Galaxies

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：