THE MOLECULAR CLOUDS FUELING A 1/5 SOLAR METALLICITY STARBURST
THE MOLECULAR CLOUDS FUELING A 1/5 SOLAR METALLICITY STARBURST
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分子云为 1/5 太阳金属性星暴提供燃料
DOI：
10.3847/0004-637x/828/1/50
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
C. Chen
中科院分区：
文献类型：
--
作者：
A. Kepley;A. Leroy;Kelsey E. Johnson;K. Sandstrom;C. Chen
使用阿塔卡马大型毫米/亚毫米阵列，我们已经取得了第一个高空间和光谱分辨率的观测分子气体和尘埃的原型蓝色致密矮星系II Zw 40。辐射呈团块状，分布在整个中心恒星形成区。八个分子云中只有一个与星星的形成有关。连续光谱能量分布主要由自由-自由和同步加速器组成;在870 μm处，只有50%的辐射来自尘埃。我们推导出一个CO到H2的转换因子使用几种方法，包括一种新的方法，使用简单的photodissocation模型和解决CO线强度测量，以获得一个关系，唯一地预测一个给定的金属丰度。我们发现CO到H2的转换因子是银河系的4-35倍（18.1-150.5）。分子气体的星星形成效率至少比正常螺旋星系高10倍，这可能是由于II Zw 40的爆发主导的星星形成历史，而不是固有的更高效率。II Zw 40内的分子云类似于其他强相互作用系统中的分子云，如超新星：总体而言，它们具有高的尺寸线宽系数和分子气体表面密度。这些性质似乎是由于高分子气体的表面密度产生在这个合并系统，而不是增加外部压力。总的来说，这些结果描绘了一幅II Zw 40作为一个复杂的，快速发展的系统，其分子气体性质是由大规模的气体冲击从其正在进行的合并占主导地位的图片。
Using the Atacama Large Millimeter/submillimeter Array, we have made the first high spatial and spectral resolution observations of the molecular gas and dust in the prototypical blue compact dwarf galaxy II Zw 40. The and emission is clumpy and distributed throughout the central star-forming region. Only one of eight molecular clouds has associated star formation. The continuum spectral energy distribution is dominated by free–free and synchrotron; at 870 μm, only 50% of the emission is from dust. We derive a CO-to-H2 conversion factor using several methods, including a new method that uses simple photodissocation models and resolved CO line intensity measurements to derive a relationship that uniquely predicts for a given metallicity. We find that the CO-to-H2 conversion factor is 4–35 times that of the Milky Way (18.1–150.5 ). The star formation efficiency of the molecular gas is at least 10 times higher than that found in normal spiral galaxies, which is likely due to the burst-dominated star formation history of II Zw 40 rather than an intrinsically higher efficiency. The molecular clouds within II Zw 40 resemble those in other strongly interacting systems like the Antennae: overall they have high size–linewidth coefficients and molecular gas surface densities. These properties appear to be due to the high molecular gas surface densities produced in this merging system rather than to increased external pressure. Overall, these results paint a picture of II Zw 40 as a complex, rapidly evolving system whose molecular gas properties are dominated by the large-scale gas shocks from its ongoing merger.
M51、M33和大麦哲伦云巨分子云的比较研究
DOI：
10.1088/0004-637x/779/1/46
发表时间：
2013
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Hughes;Colombo;Schinnerer
通讯作者：
Schinnerer
时间一瞬间——天线中恒星形成的建模
DOI：
10.1088/2041-8205/715/2/l88
发表时间：
2010
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
Johansson;Kotarba;Renaud
通讯作者：
Renaud