共查询到20条相似文献,搜索用时 15 毫秒
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Cong Huang Gang Zhao Hua-Wei Zhang Yu-Qin Chen Department of Astronomy Peking University Beijing National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2005,5(6):619-626
Using high signal-to-noise ratio spectra of extrasolar planet-hosting stars, we obtained the atmospheric parameters, accurate metallicities and the differential abundance for 15 elements (C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Ni and Ba). In a search for possible signatures of metal-rich material accreting onto the parent stars, we found that , for a given element, there is no significant trend of increasing [X/H] with increasing condensation temperature Tc. In our sample of planet-harboring stars, the volatile and refractory elements behave similarly, and we can not confirm if there exists any significant dependence on the condensation temperature Tc. 相似文献
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Hong-Xing Yin Cheng-Min Zhang Yong-Heng Zhao Li-Ming Song Fan Zhang National Astronomical Observatories Chinese Academy of Sciences Beijing Institute of High Energy Physics Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2005,5(6):595-600
For the bright neutron star low-mass X-ray binary Sco X-1, we analyzed all updated frequencies of the twin kilohertz quasi-periodic oscillations (kHz QPOs), their correlations and distributions. We found that the frequency separation of the kHz QPO peaks appears not to be a constant, rather, it decreases with increasing inferred mass accretion rate. We show that the currently available data of Sco X-1 by Rossi X-ray Timing Explorer are inconsistent with the proposals of the beat model that the frequency separation is a constant. Our conclusions are consistent with those of some previous researchers and we discuss further implications for the kilohertz QPO models. 相似文献
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2008的来到为我们的天文爱好者们迎来了一位良师益友,那就是由湖南科技出版社新出版的《剑桥天文爱好者指南》2008年1月第一版,16开本360页,部分彩印,内容丰富而实用。全书分七大部分,它们是背景知识,器材,如何观测,观测点滴,参考书目与信息,太阳系天体的观测,深空天体的观测等等。它的最大特点是展示当前欧美等天文学发达与天文爱好者比较活跃的国家中天文爱好者们的仪器设备和观测实况的资料,这些对我国天文爱好者有很高的参考价值, 相似文献
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Jun-Liang Zhao Li Chen Wen Wen Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai Shanghai University Shanghai 《中国天文和天体物理学报》2006,6(4):435-446
From photographic plate data of Shanghai Astronomical Observatory with a time baseline of 87 years, proper motions and membership probabilities of 364 stars in the open cluster NGC 6530 region are reduced. On the basis of membership determination, luminosity function and segregation effect of the cluster are discussed with details. Spatial mass segregation is obviously present in NGC 6530 while there is no clear evidence for a velocity-mass (or velocity-luminosity) dependence. The observed spatial mass segregation for NGC 6530 might be due to a combination of initial conditions and relaxation process. 相似文献
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(接上期)
象限仪:18世纪的观测主力
18世纪,天体测量方法和技术取得了巨大进步,也获得了不少新的天文发现。在确定恒星的距离方面,1718年英国天文学家埃德蒙·哈雷(Edmund Halley)通过跟古希腊时代的观测相比较,发现三颗明亮恒星的位置发生了变动。 相似文献
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人的际遇瞬息万变,人事变迁也聚散无定,在我们看来,只有“天道”的运行是亘古不变的,不会因为我们的行为而导致改变,正如古语所云“天行有常,不为尧存,不为桀亡”(《苟子·天论篇》),鲁迅先生也曾说过:“时光永是流逝,街市依旧太平”(纪念刘和珍君),天地之机,大体如是。所以人们常常会以违反常规的天文现象,来形容罕见或不可能的事件,例如“太阳打西边出来”等。但事实上,天体运行的规律看似简单而实则深刻,一些我们觉得不可思议或难得一见的天文现象,或许并不是真的就绝无可能。 相似文献
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我国古代天文学是非常发达的,诞生了很多位著名的天文学家,制造了一大批天文观测仪器,我们的祖先早在公元前就注意到了众多天文现象,并有相当数量古老、丰富的天象记录,这些对日后研究天文学做出了很多宝贵的贡献。可惜能保存下来的古代天文仪器数量较少,现存的古代仪器主要保存在北京古观象台及南京紫金山天文台上。 相似文献