论文标题
来自以冲击压缩层形成的O星的电离反馈
Ionising feedback from an O star formed in a shock-compressed layer
论文作者
论文摘要
我们开发了一个简单的分析模型，用于在冲击压缩层中形成O恒星（或紧凑的OB恒星簇）时发生的情况，并在双相HII区域（HIIR）的腰部雕刻在层中大约圆形的孔。该模型的特征是三个参数：未扰动层的半厚度，Zlay，未扰动层中氢分子的平均数密度，nlay和ndotlyc的恒星电离输出的（集体）电离输出。圆形孔的半径由wif〜3.8 pc [zlay/0.1pc]^{ - 1/6} [nlay/10^4cm^{ - 3}]^{ - 1/3} [ndotlyc/10^{49} s^{49} s^{ - 1} { - 1}]^{1/6}^{1/6} {1/6} {t/myr]对于将离子气体送入双极裂片的速率，获得了类似的幂律表达。分子气体被冲击前（SF）扫成密集的环的速率（sf）（如果）；以及该密集环中的密度。我们建议我们的模型可能是许多观察到的HIIRS的有用的零级表示。从靠近层中间平面的看方向，HIIR将出现双极性。从查看大约正常的方向到层，它似乎是肢体闪烁的外壳，但穿过中心太微弱，无法成为球形对称的气泡。从中间视角可以预期更复杂的形态。
We develop a simple analytic model for what happens when an O star (or compact cluster of OB stars) forms in a shock compressed layer and carves out an approximately circular hole in the layer, at the waist of a bipolar HII Region (HIIR). The model is characterised by three parameters: the half-thickness of the undisturbed layer, Zlay, the mean number-density of hydrogen molecules in the undisturbed layer, nlay, and the (collective) ionising output of the star(s), NdotLyC. The radius of the circular hole is given by WIF ~ 3.8 pc [Zlay/0.1pc]^{-1/6} [nlay/10^4cm^{-3}]^{-1/3} [NdotLyC/10^{49} s^{-1}]^{1/6} [t/Myr]^{2/3}. Similar power-law expressions are obtained for the rate at which ionised gas is fed into the bipolar lobes; the rate at which molecular gas is swept up into a dense ring by the shock front (SF) that precedes the ionisation front (IF); and the density in this dense ring. We suggest that our model might be a useful zeroth-order representation of many observed HIIRs. From viewing directions close to the midplane of the layer, the HIIR will appear bipolar. From viewing directions approximately normal to the layer it will appear to be a limb-brightened shell but too faint through the centre to be a spherically symmetric bubble. From intermediate viewing angles more complicated morphologies can be expected.
