Hydrodynamical models of cometary H II regions
Hydrodynamical models of cometary H II regions
复制标题
彗星 H II 区域的流体动力学模型
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
J. Pittard
中科院分区：
文献类型：
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作者：
Harrison Steggles;M. Hoare;J. Pittard
我们对由 O 和 B 光谱类型的零年龄主序星产生的彗星 H ii 区域的演化进行了建模，这些恒星驱动着强风，并且从具有幂律 (α = 2) 密度斜率的球对称核心偏离中心诞生。生成了涵盖恒星质量、年龄和核心密度的模型参数网格。为了探索这个参数空间，我们研究了边缘增亮，这是彗星 H ii 区域中常见的一个特征。我们发现质量 M⋆ ≥ 12 M⊙ 的恒星会产生这种特征。我们的模型有一个由接触不连续性所包围的空腔，该接触不连续性将热激风和电离环境气体分开，其大小与周围的 H ii 区域相似。由于早期的压力限制，对于 M⋆ ≤ 40 M⊙ 的恒星，我们没有看到接触不连续性之外的激波，但发现空腔继续生长。当 H ii 区域停滞时，每个模型中的空腔尺寸都趋于稳定。我们模型的光谱能量分布与在均匀密度场中演化的相同恒星的光谱能量分布相似。由于 H ii 区域覆盖的低密度气体比例较高，因此我们的幂律模型中的翻转频率略低。
We have modelled the evolution of cometary H ii regions produced by zero-age main-sequence stars of O and B spectral types, which are driving strong winds and are born off-centre from spherically symmetric cores with power-law (α = 2) density slopes. A model parameter grid was produced that spans stellar mass, age and core density. Exploring this parameter space, we investigated limb-brightening, a feature commonly seen in cometary H ii regions. We found that stars with mass M⋆ ≥ 12 M⊙ produce this feature. Our models have a cavity bounded by a contact discontinuity separating hot shocked wind and ionized ambient gas that is similar in size to the surrounding H ii region. Because of early pressure confinement, we did not see shocks outside of the contact discontinuity for stars with M⋆ ≤ 40 M⊙, but the cavities were found to continue to grow. The cavity size in each model plateaus as the H ii region stagnates. The spectral energy distributions of our models are similar to those from identical stars evolving in uniform density fields. The turn-over frequency is slightly lower in our power-law models as a result of a higher proportion of low-density gas covered by the H ii regions.
DOI：
10.1088/0067-0049/208/1/11
发表时间：
2013-08
期刊：
The Astrophysical Journal Supplement Series
影响因子：
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作者：
S. Lumsden;M. Hoare;J. Urquhart;R. Oudmaijer;B. Davies;J. Mottram;H. Cooper;T. U. O. Leeds;Leeds;Uk;Max Planck Institut fur Radioastronomie;Bonn;Germany;A. R. Institute;Liverpool John Moores University;Liverpool;L. Observatory;Leiden University;Leiden;The Netherlands
通讯作者：
S. Lumsden;M. Hoare;J. Urquhart;R. Oudmaijer;B. Davies;J. Mottram;H. Cooper;T. U. O. Leeds;Leeds;Uk;Max Planck Institut fur Radioastronomie;Bonn;Germany;A. R. Institute;Liverpool John Moores University;Liverpool;L. Observatory;Leiden University;Leiden;The Netherlands