H II regions and high-mass starless clump candidates: II. Fragmentation and induced star formation at ~0.025 pc scale: an ALMA continuum study
H II regions and high-mass starless clump candidates: II. Fragmentation and induced star formation at ~0.025 pc scale: an ALMA continuum study
复制标题
H−II 区域和大质量无星团块候选者：II。
DOI：
10.1051/0004-6361/202038421
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发表时间：
2021
影响因子：
6.5
通讯作者：
Pillai, T. G.
中科院分区：
文献类型：
--
作者：
Zhang, S.;Zavagno, A.;López-Sepulcre, A.;Liu, H.;Louvet, F.;Figueira, M.;Russeil, D.;Wu, Y.;Yuan, J.;Pillai, T. G.
背景来自HⅡ区的电离反馈改变了团簇尺度上的大质量无恒星团(HMSCs)的性质，如尘埃温度和湍流。HII区的存在是否改变了hMSCs的核心尺度(0.025：025pC)碎裂和恒星形成的问题仍有待探讨。目的我们旨在研究受HII区强烈影响的候选hMSCs和干扰较少的候选hMSCs之间0.025 pC尺度碎裂的差异。我们还在受影响的候选HMSCs中寻找质量形成和诱导星形成的证据。方法使用ALMA1.3 mm连续体，典型的角分辨率为1.300，成像8个候选hMSCs，其中4个受H II区影响，另外4个位于安静环境中。受影响较小的候选hMSCs是根据它们与受影响的hMSCs相似的质量和距离来选择的，以避免与这些参数相关的任何可能的偏差。我们对两种类型的候选hMSCs进行了比较。我们利用多波长数据分析了HⅡ区与受影响的候选HMSCs之间的相互作用。结果共检测到8个簇中的51个核，每个簇3~9个核。在我们有限的样本中，我们没有发现受影响和未受影响的候选hMSCs之间0：025PC级的碎裂程度的明显差异，尽管H II区域似乎影响了碎裂核心的空间分布。两种类型的候选hMSCs在簇热牛仔长度Th J；CLUMP和0.3TH J；CLUMP处都呈现具有两级分级特征的热碎裂。受影响的候选hMSCs AGAL010.214-00.306和AGAL018.931-00.029的ALMA发射形态揭示了HII区在其周围形成气体和尘埃的能力，并可能在候选HMSCs中触发0：025pC尺度的恒星形成。结论这两种候选hMSCs在0：025pC尺度上的碎裂可能以热为主，同时HII区可能具有帮助在受影响的候选hMSCs中形成致密结构的能力。未来的ALMA成像调查需要覆盖大量受影响的高湍流水平的候选hMSCs，以确认本研究所指出的碎裂趋势。
ContextThe ionization feedback from H II regions modifies the properties of high-mass starless clumps (HMSCs, of several hundred to a few thousand solar masses with a typical size of 0.1–1 pc), such as dust temperature and turbulence, on the clump scale. The question of whether the presence of H II regions modifies the core-scale ( 0:025 pc) fragmentation and star formation in HMSCs remains to be explored.AimsWe aim to investigate the difference of 0.025 pc-scale fragmentation between candidate HMSCs that are strongly impacted by H II regions and less disturbed ones.We also search for evidence of mass shaping and induced star formation in the impacted candidate HMSCs.MethodsUsing the ALMA 1.3 mm continuum, with a typical angular resolution of 1.300, we imaged eight candidate HMSCs, including four impacted by H II regions and another four situated in the quiet environment. The less-impacted candidate HMSCs are selected on the basis of their similar mass and distance compared to the impacted ones to avoid any possible bias linked to these parameters. We carried out a comparison between the two types of candidate HMSCs. We used multi-wavelength data to analyze the interaction between H II regions and the impacted candidate HMSCs.ResultsA total of 51 cores were detected in eight clumps, with three to nine cores for each clump. Within our limited sample, we did not find a clear difference in the 0:025 pc-scale fragmentation between impacted and non-impacted candidate HMSCs, even though H II regions seem to affect the spatial distribution of the fragmented cores. Both types of candidate HMSCs present a thermal fragmentation with two-level hierarchical features at the clump thermal Jeans length th J;clump and 0.3 th J;clump. The ALMA emission morphology of the impacted candidate HMSCs AGAL010.214-00.306 and AGAL018.931-00.029 sheds light on the capacities of H II regions to shape gas and dust in their surroundings and possibly to trigger star formation at 0:025 pc-scale in candidate HMSCs.ConclusionsThe fragmentation at 0:025 pc scale for both types of candidate HMSCs is likely to be thermal-dominant, meanwhile H II regions probably have the capacity to assist in the formation of dense structures in the impacted candidate HMSCs. Future ALMA imaging surveys covering a large number of impacted candidate HMSCs with high turbulence levels are needed to confirm the trend of fragmentation indicated in this study.