Diverse Nuclear Star-forming Activities in the Heart of NGC 253 Resolved with 10-pc-scale ALMA Images
Diverse Nuclear Star-forming Activities in the Heart of NGC 253 Resolved with 10-pc-scale ALMA Images
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DOI：
10.3847/1538-4357/aa8fd4
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发表时间：
2017-10
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影响因子：
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通讯作者：
R. Ando;K. Nakanishi;K. Kohno;T. Izumi;S. Martín;N. Harada;S. Takano;N. Kuno;N. Nakai;
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作者：
R. Ando;K. Nakanishi;K. Kohno;T. Izumi;S. Martín;N. Harada;S. Takano;N. Kuno;N. Nakai;
我们基于覆盖11 GHz的阿尔马波段7（或GHz）观测，给出了附近星暴星系NGC 253中心200 pc区域的8 pc × 5 pc分辨率视图。我们首次将NGC 253的核星爆分解为8个尘埃恒星形成团块，规模为10 pc。这些团块，其中每一个包含（4-10）尘埃（假设尘埃温度为25 K）和大质量（O 5V）恒星，似乎是在两个平行的山脊对齐，而他们已经在以前的研究中混合。尽管这些团块的大小和尘埃质量相似，但它们的线光谱在不同的团块之间变化很大，尽管它们之间的距离只有1000 pc。具体地说，其中一个团簇，团簇1，表现出来自19个分子的至少36条发射线的线混淆限制光谱（包括CH_3OH、HNCO、H_2CO、CH_3CCH、H_2CS和H_3 O+）和氢复合线（H_（26 α）），而在其他一些团簇中检测到的分子线种类要少得多，从光谱中完全消失我们证明了在前一个星团中存在热分子气体（K），这表明热的和化学丰富的环境局限于10 pc尺度的恒星形成星团内。
We present an 8 pc × 5 pc resolution view of the central ∼200 pc region of the nearby starburst galaxy NGC 253, based on ALMA Band 7 ( or GHz) observations covering 11 GHz. We resolve the nuclear starburst of NGC 253 into eight dusty star-forming clumps, 10 pc in scale, for the first time. These clumps, each of which contains (4–10) of dust (assuming that the dust temperature is 25 K) and up to massive (O5V) stars, appear to be aligned in two parallel ridges, while they have been blended in previous studies. Despite the similarities in sizes and dust masses of these clumps, their line spectra vary drastically from clump to clump, although they are separated by only ∼10 pc. Specifically, one of the clumps, Clump 1, exhibits line-confusion-limited spectra with at least 36 emission lines from 19 molecules (including CH3OH, HNCO, H2CO, CH3CCH, H2CS, and H3O+) and a hydrogen recombination line (H26α), while far fewer kinds of molecular lines are detected in some other clumps where fragile species, such as complex organic molecules and HNCO, completely disappear from their spectra. We demonstrate the existence of hot molecular gas ( K) in the former clump, which suggests that the hot and chemically rich environments are localized within a 10-pc-scale star-forming clump.