2008年俄罗斯天文通讯赛

总则赞助单位莫斯科大学 Sternberg 天文研究院、Lebedev 物理学院科学和教育部、欧亚天文学会、Skymart公司、Phusicon公司。竞赛冠名赞助商 Skymart公司,Celestron 公司俄罗斯总经     

联合国宣布2009年为国际天文年

在2007年12月20日的第62届联合国会员大会上,联合国宣布2009年为国际天文年。决议由伽利略的故乡意大利提交。2009年国际天文年由国际天文学联合会及联合国教科文组织共同主办。     

为什么天文不受重视

有一位署名“lazy1004”的天文爱好者给我写信,表达了一个很具有代表性的疑问：天文学在学校中为何不受重视？他（或她）写道：“同为六大自然学科,偏偏没有开设天文课,即使有。也只是一个星期才一节的选修课。给我们上课的是一位地理老师．他是一位狂热的天文爱好者,但似乎比校长还忙。学校的望远镜坏了,校方也一拖再拖,迟迟没有联系人来修。这样的选修课在他们眼中是那么的不重要。所有的人都在为考试而忙碌。这让我感到孤独。为什么？!”     

2008年12月重要天象预告

不知不觉,我们已经迎来了今年的最后一月。而璀璨的冬夜星空,以及本月几个值得期待的重要天象,也将为2008年画上圆满的句号。     

四百年的大课

10月12日,一场科学大师演讲会在人民大会堂举行。这是为了纪念望远镜发明400周年。发表演讲的科学大师共有三位,分别是诺贝尔奖得主美籍华裔科学家李政道、美籍意大利裔科学家里卡尔多·贾科尼和邵逸夫天文学奖得主美国科学家杰弗里·马西。     

An X-Ray Study of Lobe-Dominated Radio-Loud Quasars with XMM-Newton

We report on our results of X-ray spectral analysis for a sample of radio-loud quasars covering a wide range of the radio core-dominance parameter, R, from core-dominated to lobe-dominated objects, using data obtained mostly with the XMM-Newton Observatory. We find that the spectral shape of the underlying power-law continuum is flat even for the lobe-dominated objects (average photon index ～ 1.5), indistinguishable from that of core-dominated quasars. For lobe-dominated objects, contribution of X-rays from the jets is expected to be very small based on previous unification schemes, more than one order of magnitude lower than the observed X-ray luminosities. Assuming that radio-loud quasars follow the same X-ray-UV/optical luminosity relation for the disk-corona emission as found for radio-quiet quasars, we estimate the X-ray flux contributed by the disk-corona component from the optical/UV continuum. We find that neither the luminosity, nor the spectral shape, of the disk-corona X-ray emission can account for the bulk of the observed X-ray properties. Thus in lobe-dominated quasars, either the disk-corona X-ray emission is much enhanced in strength and flatter in spectral shape (photon index～1.5) compared to normal radio-quiet quasars, or their jet X-ray emission is much enhanced compared to their weak radio core-jet emission. If the latter is the case, our result may imply that the jet emission in X-rays is less Doppler beamed than that in the radio. As a demonstrating example, we test this hypothesis by using a specific model in which the X-ray jet has a larger opening angle than the radio jet.     

The Structure of Narrow-Line Region in LINERs

Low-ionization nuclear emission regions (LINERs) are present in a large fraction of local galaxies, while their connection to the more luminous active galactic nuclei (AGN) remains elusive. We analyze the narrow band images obtained by the Hubble Space Telescope (HST) in Hα [NⅡ] and/or [OⅢ] band for 23 LINERs and low luminosity Seyfert galaxies in the sample of the Palomar Optical Spectroscopic Survey of nearby galaxies in an attempt to resolve the structure of Narrow Emission Line Regions (NLRs) of these objects. In all cases, NLRs are well resolved and their morphology differs from object to object. Clumps, linear structure, spiral arms or a ring are detected in a large fraction of the objects, while there is no significant difference between Seyfert galaxies and LINERs. We find that the NLR size and the narrow line luminosity are strongly correlated for both LINERs and low luminosity Seyfert galaxies, and that the size of Hα [NⅡ] emission line region scales with Hα luminosity as RNLR∞L0.4±0.06Hα, consistent with an extension of the NLR size-luminosity relation defined for luminous Seyfert galaxies and quasars, to two orders of magnitude lower in luminosity and to lower activity levels. Our results suggest that NLRs in LINERs are similar to those of Seyfert galaxies, and they are powered by the central active galactic nucleus.     

GALEX证实暗能量的性质

15年来,国际天文学界对遥远星系中超新星的观测,除了得出宇宙加速膨胀的结论外,还推测出宇宙组成的成分：暗能量约占74％、暗物质约占22％、而包括原子、组成生物体、行星和恒星等的正常物质只占4％。