| 具局部各向同性速度分布的旋转椭球星系的长期演化 |
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| 引用本文： | 傅燕宁,孙义燧.具局部各向同性速度分布的旋转椭球星系的长期演化[J].天文学报,1998,39(2):153-164. |
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| 作者姓名： | 傅燕宁 孙义燧 |
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| 作者单位： | 中国科学院紫金山天文台!南京，210008，南京大学天文系!南京，210093 |
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| 摘 要： | Chandrasekhar等和Sunder等讨论了具有局部各向同性速度分布的旋转椭球星系的短期（远小于哈勃时间）演化，本文运用Laskar的频率分析方法研究这种星系的长期（大于哈勃时间）演化．得到的新结论主要有：（1）这种星系存在唯一的平衡态（球对称平衡态），它是临界线性稳定的;（2）其半轴一般在平衡态的半径邻近作拟周期或近拟周期（这种近似在远大于哈勃时间后仍可行）振动，从而是长期稳定的；（3）存在一个半轴趋于零，另一个半轴趋于有限值的情形，且一般趋于零的是对称轴的轴长（从而星系趋于扁平），这意味着某些盘星系可能来源于具旋转棉球构形的星系前物质．
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| 关 键 词： | 天体力学 星系动力学 星系振动 |
ON THE LONG-TERM EVOLUTION OF SPHEROIDAL GALAXIES WITH LOCALLY ISOTROPIC VELOCITY DISTRIBUTION |
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| Fu Yan-ning, Sun Yi-sui.ON THE LONG-TERM EVOLUTION OF SPHEROIDAL GALAXIES WITH LOCALLY ISOTROPIC VELOCITY DISTRIBUTION[J].Acta Astronomica Sinica,1998,39(2):153-164. |
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| Authors: | Fu Yan-ning Sun Yi-sui |
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| Abstract: | The short-term evolution of spheroidal galaxies has been explored by S.Chandrasewhar et al. and G S. Sunder et al. In mis paper, we study their long-term evolution with Laskar's method of frequency analysis. The main new results are as follows: (1) There exists a unique equilibrium, which is spherically symmetric. This eqinlibrium has a critical linear stability. (2) Generally speaking, the semi-axes exhibit quasiperiodic or nearly quasiperiodic (in a time scale longer than a Hubble time)oscillations around the radius of the above-mentioned equilibrium, so the equilibrium is practically stable. (3) There are cases in which one of the semi-axes tends fast to zero while the other to some finite value. The limit state is generally planar rather than lineal i. e. it is the symmetric send-axis that tends to zero. This implies that some disk galaxies may have originated from spheroidal pregalaxy material. |
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| Keywords: | celestial mechedcs galaxy dynamics galaxy oscillation |
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