共查询到20条相似文献,搜索用时 15 毫秒
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超新星是一些质量较大的恒星演化到晚期发生爆炸所产生的天体。它们在短时间内很明亮,一颗超新星的亮度可以相当于整个星系。超新星中有一类被称作Ia型超新星, 相似文献
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本文研究了在1993年3月28日之前发现的899颗超新星(SNe)的样本.其中277颗SNe被用来研究超新星在其母星系中的径向分布.我们研究了四个星系样本中超新星在产生单个超新星(称为一般超新星)的星系及在产生多个超新星(称为多重超新星)的星系中的径向分布.这四个星系样本为:总旋涡星系样本,Sb~SbC星系样本,SC星系样本,Sc~Sd星系样本.研究的结果表明:一多重超新星比一般超新星在其母星系中具有更集中于星系核心(大多数恒星形成发生的地方)的倾向,说明星系中心的恒星形成活动会影响多重超新星事件的发生从而影响超新星的频率分布 相似文献
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本文研究了在1993年3月28日之前发现的899颗超新星(SNe)的样本。其中277颗SNe被用来研究超新星在其母星系中的径向分布。我们研究了四个星系样本中超新星在产生单个超新星(称为一般超新星)的星系及在产生多个超新星(称为多重超新星)的星系中的径向分布。这四个星系样本为:总旋涡星系样本,Sb ̄Sbc星系样本,Sc星系样本,Sc ̄Sd星系样本。研究的结果表明:多重超新星比一般超新星在其母星系中具 相似文献
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Christopher A. Tout 《中国天文和天体物理学报》2006,6(4):461-469
A carbon-oxygen white dwarf may explode in a Type Ia supernova by accreting matter from its companion via either Roche lobe overflow or from winds, but there exists a critical accretion rate of the progenitor system for the explosion. We study the relation between the critical accretion rate and the metallicity via an AGB star approach. The result indicates that the critical accretion rate depends not only on the hydrogen mass fraction and the white dwarf mass, but also on the metallicity. The effect of the metallicity is smaller than that of the white dwarf mass. We show that it is reasonable to use the model with stellar mass 1.6 M⊙for real white dwarfs. 相似文献
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Jun Yang Xiang Liu Zhi-Qiang Shen National Astronomical Observatories/Urumqi Observatory Chinese Academy of Sciences Urumqi Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai Graduate University of the Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2005,5(6):563-570
GHz-Peaked Spectrum (GPS) radio sources are powerful and compact sources with convex spectra. With increasing observational findings, it has been realized that either Synchrotron Self-Absorption (SSA) alone or Free-Free Absorption (FFA) alone is not enough to account for all the spectral features. We present a model consisting of an SSA region partially covered by FFA plasma, and derive a composite spectral formula. By applying the model to a sample of 19 GPS sources having strong absorption, it is found that the external FFA process makes the SSA peak frequency linearly shift to a higher (observed) peak frequency. The shift indicates that the FFA does play a role at the frequency close to the observed peak frequency. 相似文献
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云南天文台天文新技术实验室工作进展 总被引:1,自引:0,他引:1
云南天文台新技术实验室成立至今已走过十几个年头,这些年来为运动天文台的发展作出了很多的贡献,从我国的第一套CCD系统到天文遥在观测,不但在天文技术领域有所发展,而且目前拥有一支老中青相结合的相对稳定的队伍,本文主要回顾了新技术室这些年来的主要工作。 相似文献
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Since Baade's photographic study of M32 in the mid 1940s, it has been accepted as an established fact that M32 is a compact dwarf satellite of M31. The purpose of this paper is to report on the findings of our investigation into the nature of the existing evidence. We find that the case for M32 being a satellite of M31 rests upon Hubble Space Telescope (HST) based stellar population studies which have resolved red-giant branch (RGB) and red clump stars in M32 as well as other nearby galaxies. Taken in isolation, this recent evidence could be considered to be conclusive in favour of the existing view. However, the conventional scenario does not explain M32's anomalously high central velocity dispersion for a dwarf galaxy (several times that of either NGC 147, NGC 185 or NGC 205) or existing planetary nebula observations (which suggest that M32 is more than twice as distant as M31) and also requires an elaborate physical explanation for M32's inferred compactness. Conversely, we find that the case for M32 being a normal galaxy, of the order of three times as distant as M31, is supported by: (1) a central velocity dispersion typical of intermediate galaxies, (2) the published planetary nebula observations, and (3) known scaling relationships for normal early-type galaxies. However, this novel scenario cannot account for the high apparent luminosities of the RGB stars resolved in the M32 direction by HST observations. We are therefore left with two apparently irreconcilable scenarios, only one of which can be correct, but both of which suffer from potentially fatal evidence to the contrary. This suggests that current understanding of some relevant fields is still very far from adequate. 相似文献
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我国的天文底片数字化工作已正式启动,选取高精度的扫描仪是该工作首要和基本的任务.对Epson公司的V750 Pro和10000XL,以及Phase One公司的PowerPhase FX+扫描仪开展了测试,结果表明,PowerPhase FX+具有较高的扫描精度,一方面,该扫描仪扫描方向的稳定性与线阵CCD方向相当,均优于0.5 μm;另一方面,通过UCAC3参考星归算结果显示,尽管PowerPhase FX+的照相式扫描会带来像场畸变,但考虑3阶底片模型后,扫描星像的位置精度较高.对于上海天文台佘山40 cm折射望远镜1987年拍摄的M79底片,扫描星像的位置精度优于0.1″. 相似文献
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Hong-Lin Lu Hong-Yan Zhou Ting-Gui Wang Zhen-Quan Zhuang Xiao-Bo Dong Jun-Xian Wang Cheng Li Department for Electronics of Science & technology University of Science Technology of China Hefei Center for Astrophysics University of Science Technology of China Hefei 《中国天文和天体物理学报》2005,5(3):221-228
We present an exercise that intends to establish a relationship between the strength of nebular emission lines and optical stellar features in the spectrum of a galaxy. After accurately subtracting the stellar continuum and the underlying stellar absorption, we made reliable measurements of the emission lines of all the galaxies in the Sloan Digital Sky Survey Data Release 2 (SDSS DR2). More than 4000 star-forming galaxies with high S/N ratio of both the stellar spectrum and the emission lines are selected. These galaxy spectra are fitted with the 10 PCs of Yip et al., after all the emission line regions have been filtered out. We find that the flux of hydrogen Balmer emission lines, Hα and Hβ can be well recovered from the PCs, while the metal lines are not well reproduced. The fluxes of Hα and Hβ measured from the PC-reconstructed spectra and from the observed spectra agree well with an rms scatter of only - 0.1 dex. This result suggests that, with moderate spectral resolution and S/N ratio, the optical stellar spectrum of a galaxy can serve as an indicator of star formation rate. 相似文献
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本文用完全动力学程式计算了Ⅰ型超新星爆发。这些模型是依据氦或碳和氧构成星核,部分地或全部地产生瞬时完成的核燃烧。计算中将动力学方程、核统计平衡、Rayleigh-Taylor不稳定性等物理过程联合起来求解。重点比较了Rayleigh-Taylor不稳定性的影响,现不能作出完全肯定的结论。计算结果列在表1、表2和图2—6中。 相似文献
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行星位于“留”的位置时,在地球上看上去相对于背景恒星的运动速度为0,即ADRS为0的时刻,行星“留”。容易从图中读出行星的两次留分别发生在MJD54998和MJD55118日。 相似文献
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我们早就从教科书中得知,当大质量恒星的寿命接近尾声的时候,它们将发生猛烈的爆炸,在我们看来,这颗原本可能毫不起眼的恒星陡然增亮数千万甚至上亿倍,就好像天上出现了一颗明亮的新星,这就是我们经常听到的“超新星”——星星并不是新的, 相似文献
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天文动力学方程数值积分中的一种有效变步法 总被引:1,自引:0,他引:1
利用积分曲线的曲率控制步长的技巧,使天文动力学方程数值解法的精度和速度有较大提高,这种方法适用于天体精密定轨以及一些精度要求高的常微分方程初值问题的数值积分。 相似文献