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151.
152.
Michael De Becker Gregor Rauw Jean-Pierre Swings 《Astrophysics and Space Science》2005,297(1-4):291-298
We present the results of an intensive spectroscopic campaign in the optical waveband revealing that Cyg OB2 #8A is an O6+O5.5
binary system with a period of about 21.9 days. Cyg OB2 #8A is a bright X-ray source, as well as a non-thermal radio emitter.
We discuss the binarity of this star in the framework of a campaign devoted to the study of non-thermal emitters, from the
radio waveband to γ-rays. In this context, we attribute the non-thermal radio emission from this star to a population of relativistic
electrons, accelerated by the shock of the wind-wind collision. These relativistic electrons could also be responsible for
a putative γ-ray emission through inverse Compton scattering of photospheric UV photons, thus contributing to the yet unidentified
EGRET source 3EG J2033+4118.
Based partly on data Obtained at the Observatoire de Haute-Provence, France. 相似文献
153.
辽东、辽西石炭系(地台型)发育,化石丰富,是研究我国北方石炭系及矿产的理想地区。华北缺失下石炭统早已成“定论”,但笔者通过植物化石研究证实东北南部存在早石炭世地层无疑,并建立了Sub-lepidodendron-Achaeocalamites-Cardiopteridiumspetsbergense组合带。与此同时,作者又在辽东、辽西石炭系下部采到了丰富的孢粉化石共36属75种,并归结为Lycosporapusilla-Crassisporakosankei组合,时代为早石炭世晚期,即维宪-纳缪尔A期。从而孢粉、植物大化石互为佐证,进一步肯定辽东、辽西存在早石炭世地层,进而改写了华北地质史的内容,并对古构造、古地理的研究具有重要意义。另外,孢粉层位还发现了丰富的叶肢介化石,这是我国石炭纪的第3处叶肢介产地,对叶肢介的起源、演化及利用多门类生物化石解决石炭系的内部界线划分积累了资料。 相似文献
154.
155.
156.
Bärbel Koribalski Eva Manthey 《Monthly notices of the Royal Astronomical Society》2005,358(1):202-210
We present H i line and 20-cm radio continuum observations of the NGC 1511 galaxy group obtained with the Australia Telescope Compact Array. The data reveal an extended, rather disturbed H i distribution for the peculiar starburst galaxy NGC 1511 and a narrow bridge to its small companion galaxy, NGC 1511B, which has been severely distorted by the interaction/collision between the two galaxies. No stellar counterpart to the gaseous bridge has been detected. In addition, we find that the peculiar optical ridge to the east of NGC 1511 is probably the stellar remnant of a galaxy completely disrupted by interactions with NGC 1511. The slightly more distant neighbour, NGC 1511A, shows a regular H i velocity field and no obvious signs of interactions.
Radio continuum emission from NGC 1511 reveals three prominent sources on top of a more diffuse, extended distribution. We derive an overall star formation rate of 7 M⊙ yr−1 . The most enhanced star formation is found in the south-eastern part of the disc, coincident with several bright H ii regions, and closest to the peculiar optical ridge. No continuum emission was detected in the companions, but NGC 1511B appears to show an H ii region at its faint western edge, closest to NGC 1511. The group displays a prime example of interaction-induced star formation activity. 相似文献
Radio continuum emission from NGC 1511 reveals three prominent sources on top of a more diffuse, extended distribution. We derive an overall star formation rate of 7 M
157.
该文介绍了目前上海天文台正在研制的小型氢原子钟的监控系统。它可监控氢钟的工作情况,实现氢钟的自动启闭、参数自动检测、自动报警,可控制综合器的频率变化、微波腔温度、氢离子流的大小。 相似文献
158.
159.
None of the tentative black-hole identifications has remained without serious difficulties. As a class, the black-hole candidates
differ in no obvious property from neutron-star binaries other than in their estimated high mass. We favour an interpretation
of the black-hole candidates as binary neutron stars surrounded by a more or less massive accretion disc 相似文献
160.
We present R-band galaxy luminosity functions (GLFs) from aspectroscopic sample of six nearby rich galaxy clusters. In addition
to individual cluster GLFs, extending to, in one case, M
R=–14, we also present composite GLFs for cluster and field galaxies toM
R=–17. All six cluster samples are consistent with the composite GLF, but there is evidence that the GLF of the quiescent population
in clusters is not universal. Furthermore, the GLF of quiescent galaxies is significantly steeper in clusters than in the
field. The overall GLF in clusters is consistent with that of field galaxies, except for the luminous tip, which is enhanced
in clusters versus the field.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献