Widespread HCO Emission in the Nuclear Starburst of M82
Widespread HCO Emission in the Nuclear Starburst of M82
复制标题
M82 核星暴中广泛的 HCO 排放
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
R. Neri
中科院分区：
文献类型：
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作者：
S. Garcia;Jesús Martín;A. Fuente;A. Usero;R. Neri
我们给出了M82核的高分辨率（~ 5 '）图像，显示存在广泛的甲酰基自由基（HCO）发射。的HCO地图，第一次获得的外部星系，揭示了存在一个结构盘的~650 pc的全直径。HCO在平面上的分布模拟了M82中其他分子/电离气体示踪剂所显示的环形态。更准确地说，环跟踪HCO，CO和H II区域嵌套，与HCO环位于分子环面的外缘。对银河云中HCO的观测表明，HCO的丰度在电离气体和分子气体之间的界面处强烈增强。在M82中测得的HCO的总体丰度令人惊讶地高[X（HCO）~ 4 × 10-10]，这表明它的核盘可以被看作是一个巨大的光子主导区（PDR），大小约为650 pc。各种嵌套气体环的存在，最高的HCO丰度出现在外圈[X（HCO）~ 0.8 × 10-9]，表明PDR化学在盘中传播。我们讨论了推断的大丰度的HCO在M82的背景下，一个星暴演化的情况下，描绘M82的核心作为一个进化的星暴。
We present a high-resolution (~5') image of the nucleus of M82 showing the presence of widespread emission of the formyl radical (HCO). The HCO map, the first obtained in an external galaxy, reveals the existence of a structured disk of ~650 pc full diameter. The HCO distribution in the plane mimics the ring morphology displayed by other molecular/ionized gas tracers in M82. More precisely, rings traced by HCO, CO, and H II regions are nested, with the HCO ring lying in the outer edge of the molecular torus. Observations of HCO in Galactic clouds indicate that the abundance of HCO is strongly enhanced in the interfaces between the ionized and molecular gas. The surprisingly high overall abundance of HCO measured in M82 [X(HCO) ~ 4 × 10-10] indicates that its nuclear disk can be viewed as a giant photon-dominated region (PDR) of ~650 pc size. The existence of various nested gas rings, with the highest HCO abundance occurring at the outer ring [X(HCO) ~ 0.8 × 10-9], suggests that PDR chemistry is propagating in the disk. We discuss the inferred large abundances of HCO in M82 in the context of a starburst evolutionary scenario, picturing the M82 nucleus as an evolved starburst.