检索结果-南通市图书馆

Planet Host Stars: Mass, Age and Kinematics

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 151-160页

作者： yu-Qin chen and gang zhao National {3. observatories, chinese academy of sciences, beijing 100012 National astronomical observatories Chinese Academy of Sciences Beijing 100012

We determine the mass, age and kinematics of 51 extra-solar planet host stars. The results are then used to search for signs of connection of the data with metallicity and to investigate the population nature. We find that the increase in mean metallicity with stellar mass is similar to that in normal field stars, so it seems unsuitable to use this relation as a constraint on the theory of planet formation. The age and kinematic distributions seem to favour the metallicity of extra-solar planet host stars being initial. Although the kinematic data of these stars indicate their origin from two populations - the thin and the thick disks, kinematics may not help in the maintenance of the planet around the host. Stars with planets, brown dwarfs or stellar companions are sorted into three groups and re-investigated separately for their formation mechanism. The main results indicate that stars with M2 3.have [Fe/H] > 0.1 and a wide period range, but there are no other differences. Thus, there does not seem to be any physically distinguishable characteristics among the three star groups.

关键词： stars: masses ages ─ stars: kinematics -planetary system

Information from the Kinematics of F and G Stars in the Solar Neighborhood

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Astronomy and Astrophysics 2002年第5期2卷 419-428页

作者： yu-Qin chen, gang zhao and Jian-Rong ShiNational {3. observatories, chinese academy of sciences, beijing 100012 National astronomical observatories Chinese Academy of Sciences Beijing 100012

We have calculated the orbital parameters for 90 stars in chen et al. and updated the kinematic data for stars in Edvardsson et al. by using the accurate Hipparcos parallaxes and proper motions, and recalculated the α-element abundances in Edvardsson et al. in a way consistent with chen et al. The two sets of data are combined in a study of stellar populations and characteristics of F & G stars in the solar neighborhood. We confirm the result of chen et al. that a distinguishable group of stars may belong to the thick disk rather than the thin disk. The ages for the stars are determined using the theoretical isochrones of VandenBerg et al. The age-metallicity relation is investigated for different subgroups according to distance from the sun and galactic orbital parameters. It is found that a mixing of stars with different orbital parameters significantly affect the age-metallicity relation for the disk. Stars with orbits confined to the solar circle all have metallicities [Fe/H] > -0.3.irrespective of their distances from the sun or from the Galactic plane.

关键词： stars: kinematics - Galaxy: evolution - Galaxy: solar neighborhood

Metallicity calibration for solar type stars based on red spectra

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2011年第5期11卷 563-576页

作者： Jing-Kunzhao gangzhao {3.-Qinchen A-LiLuo KeyLaboratoryofOpticalAstronomy NationalAstronomicalObservatoriesChineseAcademyofSciencesBeijing100012China

Based on a high resolution and high signal-to-noise ratio （S/N） spectral analysis of 90 solar-type stars, we have established several new metaUicity calibrations in the Tefr range [5600, 6500] K based on red spectra with the wavelength range of 560-880 nm. The new metallicity calibrations are applied to determine the metallicity of solar analogs selected from Sloan Digital Sky Survey （SDSS） spectra. There is a good consistent result with the adopted value presented in SDSS-DR7 and a small scatter of 0.26 dex for stars with S/N 〉 50 being obtained. This study provides a new reliable way to derive the metallicity for solar-like stars with low resolution spectra. In particular, our calibrations are useful for finding metal-rich stars, which are missing in the SEGUE Stellar Parameter Pipeline.

关键词： techniques: radial velocities - stars: temperatures - stars: abundances

Spectral analysis of two solar twins and the colors of the Sun

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2010年第8期53卷 579-585页

作者： zhao ZhengShi1,2, chen yuQin1, zhao JingKun1 & zhao gang1 1 National astronomical observatories, chinese academy of sciences, beijing 100012, China 2 Graduate University of chinese academy of sciences, beijing 100049, China 1. National astronomical observatories Chinese Academy of Sciences Beijing 100012 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

High resolution (R^40,000) and high signal-to-noise ratio (>150) spectra of two solar twins, HD14623. and HD19503., are obtained with the Coude Echelle Spectrograph at the 2.16 m telescope of the National astronomical observatories of chinese academy of sciences (Xinglong, China). Based on the detailed spectrum match, comparisons of chemical composition and chromospheric activity, HD14623. and HD19503. are confirmed that they are similar to the Sun except for lithium abundance, which is higher than the solar value. Moreover, among nine solar twin candidates (including HD14623. and HD19503.) found in the previous works, we have picked out six good solar twin candidates based on newly-derived homogenous parameters, and collected their colors in the Johnson/Cousins, Tycho, 2MASS and Strmgren system from the literature. The average color are (B-V)⊙=0.644 mag, (V-Ic)⊙=0.707 mag, (BT-VT)⊙=0.725 mag, (J-H)⊙=0.288 mag, (H-K)⊙=0.066 mag, (v-y)⊙=1.028 mag, (v-b)⊙=0.619 mag, (u-v)⊙=0.954 mag and (b-y)⊙=0.409 mag, which represent the solar colors with higher precision than previous works.

关键词： Sun-colors Star-atmospheres abundances fundamental parameters

同方期刊数据库

Narrow line Seyfert 1 galaxies: where are the broad line regions?

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2010年第12期53卷 2307-2311,2339-2343页

作者： MAO WeiMing 1,2,3., HU chen 2 , WANG JianMin 2 , BIAN WeiHao 4 , ZHANG Shu 2 & zhao gang 1 1 Key Laboratory of Optical Astronomy, National {3. observatories, chinese academy of sciences, beijing 100012, China 2 Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, chinese academy of sciences, beijing 100049, China 3.Graduate University of the chinese academy of sciences, beijing 100049, China 4 Department of Physics, Nanjing Normal University, Nanjing 210011, China 1. Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China2. Key Laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China3. Graduate University of the Chinese Academy of Sciences Beijing 100049 China4. Department of Physics Nanjing Normal University Nanjing 210011 China

A sample consisting of 211 narrow line Seyfert 1 galaxies (NLS1s) with high quality spectra from the Sloan Digital Sky Survey (SDSS) is selected to explore where broad line regions are in these objects. We find that the Hβ profile can be fitted well by three (narrow, intermediate and broad) Gaussian components, and the FWHM ratios of the broad to the intermediate components hold a constant of 3.0 roughly for the entire sample. If the broad components originate from the region scaled by the well-determined Hβ reverberation mapping relation, we find that the intermediate components originate from the inner edge of the torus, which is scaled by dust K-band reverberation. We find that the IC and the BC are strongly linked dynamically, but the relation of their covering factors is much more relaxed, implying that both regions are clumpy.

关键词： black hole physics galaxies: evolution quasars: general

Study of the primordial lithium abundance

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2011年第S1期54卷 67-72页

作者： LI Zhihong1, LI ErTao1, SU Jun1, LI yunJu1, BAI XiXiang1, GUO Bing1, WANG YouBao1, chen YongShou1, HOU SuQing1, ZENG Sheng1, LIAN {3.1, SHI JianRong2 & LIU WeiPing1 1 China Institute of Atomic Energy, beijing 102413. China 2National astronomical observatories, chinese academy of sciences, beijing 100012, China China Inst Atom Energy Beijing 102413 Peoples R China chinese Acad Sci Natl Astron Observ Beijing 100012 Peoples R China

Lithium isotopes have attracted an intense interest because the abundance of both 6Li and 6Li from big bang nucleosynthesis (BBN) is one of the puzzles in nuclear astrophysics. Many investigations of both astrophysical observation and nucleosynthesis calculation have been carried out to solve the puzzle, but it is not solved yet. Several nuclear reactions involving lithium have been indirectly measured at China Institute of Atomic Energy, beijing. The Standard BBN (SBBN) network calculations are then performed to investigate the primordial Lithium abundance. The result shows that these nuclear reactions have minimal effect on the SBBN abundances of 6Li and 7Li.

关键词： big bang nucleosynthesis element abundance nuclear reaction network

Three Super Active Regions in the Descending Phase of Solar Cycle 23

在线全文

学校读者我要写书评

暂无评论

chinese Journal of Astronomy and Astrophysics 2003年第6期3卷 491-494页

作者： hong-Qi Zhang, Xing-Ming Bao, Yin Zhang, Ji-hong Liu, Shu-Dong Bao, yuan-Yong Deng, Wei Li, Jie {3., Jin-Ping Dun, Jiang-Tao Su, Juan Guo, Xiao-Fan Wang, Ke-Liang Hu, gang-Hua Lin and Dong-Guang WangNational astronomical observatories, chinese academy of sciences, beijing 100012 National astronomical observatories CAS NAOC Beijing 100012 China

We analyze the magnetic configurations of three super active regions, NOAA 10484, 10486 and 10488, observed by the Huairou Multi-Channel Solar Telescope (MCST) from 2003.October 18 to November 4. Many energetic phenomena, such as flares (including a X-28 flare) and coronal mass ejections (CMEs), occurred during this period. We think that strong shear and fast emergence of magnetic flux are the main causes of these events. The question is also of great interest why these dramatic eruptions occurred so close together in the descending phase of the solar cycle.

关键词： Sun: activity - Sun: flares - Sun: magnetic fields

Test observations that search for metal-poor stars with the Guoshoujing Telescope (LAMOST)

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2010年第8期10卷 753-760页

作者： Hai-Ning Li gang zhao Norbert Christlieb A-Li Luo Jing-Kun zhao Yong-Heng zhao Jian-Jun {3. Zhong-Rui Bai Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of chinese academy of sciences Beijing 100049 China Zentrum fur Astronomie der Universitat Heidelberg Landessternwarte Konigstuhl 12 69117 Heidelberg Germany

Metal-deficient stars are regarded as fossils of the early generation of stars and therefore make crucial observational targets related to stellar astrophysics. They provide fundamental information and insights on properties of the very early stage of the chemical history of the Galaxy and have been investigated for decades. The unique design of the Guoshoujing Telescope （LAMOST）, such as its large field and multi-object observational capability, enables it to be an excellent tool for searching for these metal-poor stars in the Milky Way. This work reports the result of test observations which search for metal-poor stars with LAMOST, during which nine candidate metal-poor stars with [Fe/H] ≤ - 1.0 were newly detected based on the low-resolution spectroscopic observations of the LAMOST commissioning data. The sample of stars demonstrates the efficiency of selecting from the input catalog, as well as the ability of LAMOST to enlarge the sample of metal-poor stars in the Milky Way. Furthermore, the sample of stars could be used for future calibrations of the LAMOST stellar pa- rameter pipeline.

关键词： Galaxy stellar content -- surveys -- stars Population Ⅱ

在线全文

学校读者我要写书评

暂无评论

彗木相撞中的波动

天文学报 2003年第4期44卷 337-341页

作者：陈道汉包纲中国科学院紫金山天文台南京210008 中国科学院国家天文台北京100012

1994年7月18日至24日期间,彗星苏梅克-列维9(SL-9)的超过20块碎片与木星发生了相撞.哈勃空间望远镜(HST)拍摄到的图像揭示了木星大气对撞击的动力学响应.具有重要意义的是观测到5个撞击点周围的圆环,它们以450米/秒的常速度向外运动.环... 详细信息

1994年7月18日至24日期间,彗星苏梅克-列维9(SL-9)的超过20块碎片与木星发生了相撞.哈勃空间望远镜(HST)拍摄到的图像揭示了木星大气对撞击的动力学响应.具有重要意义的是观测到5个撞击点周围的圆环,它们以450米/秒的常速度向外运动.环的圆形性表明它们是波.因为对于不同大小的撞击,波速是常量,可以推断出传播速度与爆炸能量无关.这意味着这些波动是线性波. 评述现行理论所使用的3.候选波,亦即惯性引力波、声波和地震波,介绍的重点是前面两种.

关键词：波动行星木星彗星