Dynamical Evolution of Globular Clusters

球状星团的动力学演化

• 批准号: 60540159
• 负责人: INAGAKI Shogo
• 金额: $ 1.28万
• 依托单位: Kyoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60540159/
• 关键词: Stellar dynamics; Globular clusters; Post-collapse Evolution

It is known that the cores of globular clusters evolve toward higher density states due to two-body gravitational interactions. When the densities of the cores become higher than a certain value, we have to take into account other interactions. We call the evolution of this stage post-collapse evolution. Investigations of post-collapse evolution of globular clusters become one of the most important problems in theoretical astrophysics.In this project we treated stars as point masses and neglected the effects of finite size of stars.In 1985 fiscal year we studied the evolution of cores of globular clusters with N-body numerical experiments. When the core densities of globular clusters become sufficiently high, hard binaries are formed inside the cores. The binaries interact with field stars and reversal of core contraction occurs. However, when the binding energies of the binaries become large enough, the binaries are ejected from the cores and the cores contract again. The densities of … More the cores become high again and hard binaries are formed. This leads to the reexpansion of the cores. Thus the oscillations of the core density were found to be due to the activity of hard binaries.In 1986 fiscal year N-body codes were vectorized with the collaboration of Dr. S.J. Aarseth, Institute of Astronomy, University of Cambridge. As the result, the computations with N-body code were speeded up more than ten times.Though N-body experiments are speeded up, a large amount of computational time is still necessary. Therefore it is impossible to follow the long-term evolution of globular clusters. We are attempting to follow the long-term evolution of cores of globular cluster by making simple models. We have known the probability of formation of binaries, the rate of interaction between binaries and field stars, and the rate of energy production. We are making models of cores of globular clusters with the use of these data. This investigation is under progress now and we have not got definite conclusions yet. Less

由于两体引力相互作用，球状星团的核心向高密度态演化。当核的密度变得高于某个值时，我们必须考虑其他相互作用。我们把这一阶段的演化称为后崩溃演化。球状星团坍缩后演化的研究是理论天体物理学中的重要问题之一，在本项目中，我们把恒星看作点质量，忽略了恒星有限尺寸的影响，在1985财政年度，我们用N体数值实验研究了球状星团核的演化。当球状星团的核心密度变得足够高时，在核心内部会形成硬双星。双星与场星相互作用，核心收缩发生逆转。然而，当双星的结合能变得足够大时，双星被从核心中弹出，核心再次收缩。的密度 ...更多信息 核再次变高并形成硬二进制。这导致了核心的再膨胀。1986财政年度，在剑桥大学天文研究所的S.J. Aarseth博士的合作下，N体编码被矢量化。结果表明，N体程序的计算速度提高了十倍以上，虽然N体实验的速度得到了提高，但仍然需要大量的计算时间。因此，不可能跟踪球状星团的长期演化。我们试图通过简单的模型来跟踪球状星团核心的长期演化。我们已经知道了双星形成的概率，双星和场星之间相互作用的速率，以及能量产生的速率。我们正在利用这些数据制作球状星团核心的模型。这项调查正在进行中，我们还没有得到明确的结论。少

项目成果

S.Inagaki: Proc.Third Asian-Pacific Regional Meeting of the IAU,Astrophys.Space Sci.118. 367-370 (1986)

S.Inagaki：国际天文学联合会第三次亚太区域会议议程，天体物理学.空间科学.118。

R. Elson: "Dynamical Evolution of Globular Clusters." Ann. Rev. Astron. Astrophys.(1987)

R. Elson：“球状星团的动态演化。”

E.Bettwieser: Monthly Notices Roy.Astron.Soc.213. 473-483 (1985)

E.Bettwieser：月度通知 Roy.Astron.Soc.213。

S. Inagaki: "Evolution of Globular Clusters after Gravothermal Catastrophe." Theoretical Aspect on Structure, Activity, and Evolution of Galaxies. III. ed. S. Aoki and Y. Yoshii. 57-64 (1985)

S. Inagaki：“重力灾难后球状星团的演化。”

S. Inagaki: "Post-Collapse Evolution of Globular Clusters with Finite Number of Stars in the Core." Publ. Astron. Soc. Japan. 38. 853-863 (1986)

S. Inagaki：“核心恒星数量有限的球状星团的塌缩后演化。”