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arXiv 0909.1961astro-ph.CO
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孤立星系中的星暴:ISM模型的影响

Starbursts in Isolated Galaxies: the influence of the ISM model

Christian Theis, Joachim Koeppen

摘要:

我们研究了孤立的恒星形成矮星系的稳定性,这些星系经历了由恒星反馈引起的动力驱动的星暴。在这里,我们专注于所采用的ISM模型的影响,即无论是扩散或集群。我们应用一个单区模型扩展为积极的动力学演化。我们发现了两种主要类型的重复性恒星爆发:一组(A型)的准周期性恒星爆发与星系的动力学时标。在这种情况下,恒星的形成遵循由衰减维里振荡引起的气体密度的变化。第二组(B型)恒星爆发的特征是由动力和耗散时间尺度的总和给出的长静止期:在第一次爆发后,插入的能量导致系统的大幅膨胀,从而停止任何重要的恒星形成活动。当气体再次达到高密度时,也就是说,在气体消失和恒星反馈注入的能量消散之后,下一次爆发可能会发生。在扩散ISM模型的情况下,由于辐射冷却的高效率,A型爆发是最常见的类型(没有发现B型爆发)。爆发主要发生在初始过渡阶段。在cluphilism模式(即非弹性云-云碰撞的耗散)的情况下,耗散时间尺度是动力学时间的量级或更长。这允许A型突发和B型突发两者。

英文摘要:

We study the stability properties of isolated star forming dwarf galaxies which undergo dynamically driven starbursts induced by stellar feedback. Here we focus on the impact of the adopted ISM model, i.e. either a diffuse or a clumpy ISM. We apply a one-zone model extended for active dynamical evolution. We found two major types of repetitive star bursts: one set (type A) of quasi-periodic starbursts is related to the dynamical timescale of the galaxy. In that case, the star formation follows the variations of the gas density induced by decaying virial oscillations. The second set (type B) of starbursts is characterized by long quiescence periods given by the sum of the dynamical and the dissipative timescale: after a first burst, the inserted energy leads to a substantial expansion of the system, by this stopping any significant star formation activity. A next burst might occur, when the gas reaches high densities again, i.e. after the gas recollapsed and the energy injected by stellar feedback is dissipated. In case of a diffuse ISM model, type A bursts are the most common type due to the high efficiency of radiative cooling (no type B bursts are found). Bursts occur then mainly during an initial transitory phase. In case of a clumpy ISM model (i.e. dissipation by inelastic cloud-cloud collisions), the dissipative timescale is of the order of the dynamical time or longer. This allows for both, type A and type B bursts.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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