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arXiv 0804.0439astro-ph
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[Ne II ]致密和超致密H II区气体运动的观测

[Ne II] Observations of Gas Motions in Compact and Ultracompact H II Regions

Qingfeng Zhu, John H. Lacy, Daniel T. Jaffe, Matthew J. Richter, Thomas K. Greathouse

备注：
79 pages, 48 figures, 2 tables, accepted for publication in The Astrophysical Journal Supplement. The orders of figure 47 and 48 are corrected
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摘要：

我们提出了高空间和光谱分辨率的观测16银河系的紧凑和超紧凑的H II地区的[Ne II] 12.8微米的精细结构线。氖线的小热宽度和高动态范围的地图提供了一个前所未有的观点紧凑和超紧凑的H II区域的运动学。这些观察结果巩固了我们早期对G29.96-0.02和Mon R2 IRS 1的研究中提出的超紧凑H II区域结构的新图像;系统的表面流，而不是湍流或体积膨胀，主导了H II区域的气体运动。观测结果表明，几乎所有的源都有明显的速度梯度（5-20 km/s），而且大多数源都是边缘增亮的。在许多情况下，速度模式意味着沿着电离气体的致密壳层的切向流动。没有一个观测到的源明确地符合填充膨胀球、膨胀壳、填充泡状流或由快速移动的恒星形成的彗星H II区的类别。相反，运动学和形态的大部分来源导致的图片H II区域局限于由恒星风冲压压力和沿腔表面流动的腔的边缘。在无线电连续谱和[Ne II]形态一致的来源中，大多数离子发射相对于附近的分子气体蓝移。这是一致的来源躺在近侧的出生云较少受到灭绝和气体运动主要是向外，预计压力驱动的流量。

英文摘要：

We present high spatial and spectral resolution observations of sixteen Galactic compact and ultracompact H II regions in the [Ne II] 12.8 microns fine structure line. The small thermal width of the neon line and the high dynamic range of the maps provide an unprecedented view of the kinematics of compact and ultracompact H II regions. These observations solidify an emerging picture of the structure of ultracompact H II regions suggested in our earlier studies of G29.96-0.02 and Mon R2 IRS1; systematic surface flows, rather than turbulence or bulk expansion, dominate the gas motions in the H II regions. The observations show that almost all of the sources have significant (5-20 km/s) velocity gradients and that most of the sources are limb-brightened. In many cases, the velocity pattern implies tangential flow along a dense shell of ionized gas. None of the observed sources clearly fits into the categories of filled expanding spheres, expanding shells, filled blister flows, or cometary H II regions formed by rapidly moving stars. Instead, the kinematics and morphologies of most of the sources lead to a picture of H II regions confined to the edges of cavities created by stellar wind ram pressure and flowing along the cavity surfaces. In sources where the radio continuum and [Ne II] morphologies agree, the majority of the ionic emission is blue-shifted relative to nearby molecular gas. This is consistent with sources lying on the near side of their natal clouds being less affected by extinction and with gas motions being predominantly outward, as is expected for pressure-driven flows.

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