Star cluster formation and cloud dispersal by radiative feedback: dependence on metallicity and compactness
Star cluster formation and cloud dispersal by radiative feedback: dependence on metallicity and compactness
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辐射反馈的星团形成和云扩散：对金属丰度和致密性的依赖
DOI：
10.1093/mnras/staa2062
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Fukushima;H.;Yajima;H.;Sugimura;K.;Hosokawa;T.;Omukai;K.;& Matsumoto;T.
我们通过一套3D辐射流体力学模拟，研究了不同金属丰度和柱状密度的环境中星团的形成。我们发现来自大质量恒星的光致电离反馈控制着恒星形成云中的恒星形成效率，其影响敏感地依赖于气体金属度Z和初始云表面密度Σ。ATZ=1-Z⊙，超临界流体能量从Σ=10 M⊙PC−2时的0.03at增加到0.3at。在低金属丰度的情况下，星团是由原子热气体形成的，因为分子形成时间相对于冷却或动力学时间不够短。此外，由于冷却效率较低，整个云团更容易被温度较高的海泡所破坏。尘埃衰减越小，来自附近大质量恒星的电离辐射反馈就越强，并以致密的团块终止恒星的形成。这些效应导致了在低金属丰度环境下低效的恒星形成：与z=1∼Z⊙的结果相比，无论Σ如何，超临界效率都下降了∼3atz=10−2z⊙。新生的星团在引力作用下也不受束缚。我们进一步发展了一个新的半解析模型，它可以很好地再现模拟结果，特别是观测到的SFE与云表面密度和金属密度的依赖关系。
We study star cluster formation in various environments with different metallicities and column densities by performing a suite of 3D radiation hydrodynamics simulations. We find that the photoionization feedback from massive stars controls the star formation efficiency (SFE) in a star-forming cloud, and its impact sensitively depends on the gas metallicityZand initial cloud surface density Σ. AtZ= 1 Z⊙, SFE increases as a power law from 0.03 at Σ = 10 M⊙pc−2to 0.3 at. In low-metallicity cases, star clusters form from atomic warm gases because the molecule formation time is not short enough with respect to the cooling or dynamical time. In addition, the whole cloud is disrupted more easily by expanding Hiibubbles that have higher temperature owing to less efficient cooling. With smaller dust attenuation, the ionizing radiation feedback from nearby massive stars is stronger and terminate star formation in dense clumps. These effects result in inefficient star formation in low-metallicity environments: the SFE drops by a factor of ∼3 atZ= 10−2Z⊙compared to the results forZ= 1 Z⊙, regardless of Σ. Newborn star clusters are also gravitationally less bound. We further develop a new semi-analytical model that can reproduce the simulation results well, particularly the observed dependencies of the SFEs on the cloud surface densities and metallicities.