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宇宙膨胀的发现
1923年,俄罗斯宇宙学家亚历山大·弗里德曼首先用∧=0的爱因斯坦场方程建立了宇宙学膨胀模型(∧为宇宙学常数),他发表论文阐述了膨胀宇宙的思想,即曲率分别为正、负、零时的三种情况,称为弗里德曼宇宙模型。 相似文献
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珀尔马特领导的超新星宇宙学计划(SCP)小组最初对超新星观测研究中的许多困难并不完全了解,随着他们逐渐接近成功,天文学家们开始看到此项研究的前途并出现竞争。澳大利亚国立大学的施密特和美国约翰.霍普金斯大学的里斯等人也实施超新星观测项目。 相似文献
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We present high spatial resolution X-ray spectroscopy of the supernova remnant Cassiopeia A with the Chandra observations. The X-ray emitting region of this remnant was divided into 38 × 34 pixels of 10″× 10″ each. Spectra of 960 pixels were created and fitted with an absorbed two component non-equilibrium ionization model. From the results of the spectral analysis we obtained maps of absorbing column density, temperatures, ionization ages, and the abundances of Ne, Mg, Si, S, Ca and Fe. The Si, S and possibly Ca abundance maps show obvious jet structures, while Fe does not follow the jet but seems to be distributed perpendicular to it. The abundances of Si, S and Ca show tight correlations between one another over a range of about two dex. This suggests that they are ejecta from explosive Oburning and incomplete Si-buming. Meanwhile, the Ne abundance is well correlated with that of Mg, indicating them to be the ashes of explosive C/Ne burning. The Fe abundance is positively correlated with that of Si when the latter is lower than 3 times the solar value, and is negatively correlated when higher. We suggest that such a two phase correlation is due to the different ways in which Fe was synthesized. 相似文献
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对Ⅱ型超新星瞬发爆炸模型的成功爆炸给出了一个简单明了的判据,即成功爆炸的必要提铁星核外区的质量小于0.43M⊙(Moc=Mcore-MIC〈0.43M⊙);充分条件是激波的能量大于铁核外区的质量乘以20foes。采用“等效厚度”的方法,由数值计算结果加以论证。 相似文献
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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%。 相似文献
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SN 2006oz is a super-luminous supernova with a mysterious bright precursor that has resisted explanation in standard models.However,such a precursor has been predicted in the dual-shock quark nova model of super-luminous supernovae–the precursor is the supernova event while the main light curve of the super-luminous supernova is powered by the Quark-Nova(explosive transition of the neutron star to a quark star).As the supernova is fading,the Quark-Nova re-energizes the supernova ejecta,producing a"double-humped"light curve.We show that the quark nova model successfully reproduces the observed light curve of SN 2006oz. 相似文献
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In recent years a number of double-humped supernovae (SNe) have been discovered. This is a feature predicted by the dual-shock Quark-Nova (QN) model where an SN explosion is followed (a few days to a few weeks later) by a QN explo- sion. SN 2009ip and SN 2010mc are the best observed examples of double-humped SNe. Here, we show that the dual-shock QN model naturally explains their light curves including the late time emission, which we attribute to the interaction between the mixed SN and QN ejecta and the surrounding circumstellar matter. Our model applies to any star (O-stars, luminous blue variables, Wolf-Rayet stars, etc.) provided that the mass involved in the SN explosion is ~ 20 Mo which provides good conditions for forming a QN. 相似文献