On the formation and expansion of H II regions
On the formation and expansion of H II regions
复制标题
H II 区的形成和扩展
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
P. Bodenheimer
中科院分区：
文献类型：
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作者：
J. Franco;G. Tenorio;P. Bodenheimer
H II区域的演变球形云小，恒定密度的核心和幂律密度分布r exp -W的核心外解析描述。发现存在一个临界指数，超过这个指数，云就完全电离了。它在形成阶段的值取决于初始条件，但在膨胀阶段，它具有明确定义的值w（crit）= 3/2。对于w小于w（临界），H II区域的半径以给定的速率增长，而中性质量积累在电离和冲击波前之间的相间。对于w = w（临界），波前一起移动，没有质量积累。w大于w（临界）的情况导致香槟阶段：一旦云被完全电离，膨胀就变成超音速。对于没有磁场的自引力盘，主要特征包括一个新的可变大小的阶段。H II区的初始形状有一个临界点，超过这个临界点，盘就完全电离了。参考文献40篇。
The evolution of H II regions in spherical clouds with small, constant-density cores and power-law density distributions r exp -w outside the core is described analytically. It is found that there is a critical exponent above which the cloud becomes completely ionized. Its value in the formation phase depends on the initial conditions, but it has a well-defined value w(crit) = 3/2 during the expansion phase. For w less than w(crit), the radius of the H II region grows at a given rate, while neutral mass accumulates in the interphase between the ionization and shock fronts. For w = w(crit), the fronts move together without mass accumulation. Cases with w greater than w(crit) lead to the champagne phase: once the cloud is fully ionized, the expansion becomes supersonic. For self-gravitating disks without magnetic fields, the main features include a new variable-size stage. The initial shape of the H II region has a critical point beyond which the disk becomes completely ionized. 40 refs.