IRAS 23385+6053: an embedded massive cluster in the making
IRAS 23385+6053: an embedded massive cluster in the making
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DOI：
10.1051/0004-6361/201935506
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发表时间：
2019-05
影响因子：
6.5
通讯作者：
R. Cesaroni;H. Beuther;A. Ahmadi;M. Beltrán;T. Csengeri;R. Galván-Madrid;C. Gieser;T. Henning;K. Johnston;P. Klaassen;R. Kuiper;S. Leurini;H. Linz;S. Longmore;S. Lumsden;L. Maud;L. Moscadelli;J. Mottram;A. Palau;T. Peters;R. Pudritz;Á. Sánchez-Monge;P. Schilke;D. Semenov;S. Suri;J. Urquhart;J. Winters;Qizhou Zhang;H. Zinnecker
中科院分区：
文献类型：
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作者：
R. Cesaroni;H. Beuther;A. Ahmadi;M. Beltrán;T. Csengeri;R. Galván-Madrid;C. Gieser;T. Henning;K. Johnston;P. Klaassen;R. Kuiper;S. Leurini;H. Linz;S. Longmore;S. Lumsden;L. Maud;L. Moscadelli;J. Mottram;A. Palau;T. Peters;R. Pudritz;Á. Sánchez-Monge;P. Schilke;D. Semenov;S. Suri;J. Urquhart;J. Winters;Qizhou Zhang;H. Zinnecker
背景。这项研究是CORE项目的一部分，CORE是IRAM/NOEMA的一个大型项目，包括对20个选定的大质量恒星形成区域的毫米波连续谱和分子谱线发射的观测。该项目的目标是寻找星周吸积盘，研究分子团块的分裂过程，并调查这些区域中气体的化学成分。
目的。我们聚焦于IRAS 23385 + 6053，它被认为是CORE样本中演化程度最低的源。这个天体的特征是一个紧凑的分子团块，在24μm以下是红外暗的，并被在近红外波段探测到的一个恒星集群所环绕。我们的目的是研究该团块的结构和速度场。
方法。观测是在约1.4毫米波段进行的，采用了NOEMA的三种配置以及额外的单碟图，并与干涉测量数据合并以恢复扩展发射。我们的相关器设置涵盖了来自著名的热核示踪物和一些外流示踪物的多条谱线。角分辨率（约0′′.45 - 0′′.9）和光谱分辨率（0.5 km s⁻¹）足以分辨IRAS 23385 + 6053中的团块，并研究由于旋转、下落或膨胀引起的大规模运动的存在。
结果。我们发现，当以亚角秒分辨率观测时，团块分裂为六个不同的核心。这些核心通过它们在1.4毫米连续谱和分子谱线发射得以识别。我们绘制了来自甲醇和甲基氰谱线的速度、线宽和转动温度图，这使我们能够研究这些核心，并揭示出最大质量核心中的速度和温度梯度。我们还发现了双极外流的证据，可能由一颗低质量恒星驱动。
结论。我们初步探测到位于最大质量核心中的一个星周自引力盘，它驱动着文献中先前已知的大规模外流。在我们的设想中，驱动外流的恒星是IRAS 23385 + 6053大部分光度（约3000 L⊙）的来源。其他核心尽管质量低于相应的位力质量，但似乎正在从其分子环境中吸积物质，并且可能正在坍缩或处于坍缩的边缘。我们得出结论，我们正在观测的是一组恒星形成核心样本，它们必然会转变为一个大质量恒星集群。
Context. This study is part of the CORE project, an IRAM/NOEMA large program consisting of observations of the millimeter continuum and molecular line emission towards 20 selected high-mass star-forming regions. The goal of the program is to search for circumstellar accretion disks, study the fragmentation process of molecular clumps, and investigate the chemical composition of the gas in these regions. Aims. We focus on IRAS 23385+6053, which is believed to be the least-evolved source of the CORE sample. This object is characterized by a compact molecular clump that is IR-dark shortward of 24 μm and is surrounded by a stellar cluster detected in the near-IR. Our aim is to study the structure and velocity field of the clump. Methods. Observations were performed at ~1.4 mm and employed three configurations of NOEMA and additional single-dish maps, merged with the interferometric data to recover the extended emission. Our correlator setup covered a number of lines from well-known hot core tracers and a few outflow tracers. The angular (~0′′.45–0′′.9) and spectral (0.5 km s−1) resolutions were sufficient to resolve the clump in IRAS 23385+6053 and investigate the existence of large-scale motions due to rotation, infall, or expansion. Results. We find that the clump splits into six distinct cores when observed at sub-arcsecond resolution. These are identified through their 1.4 mm continuum and molecular line emission. We produce maps of the velocity, line width, and rotational temperature from the methanol and methyl cyanide lines, which allow us to investigate the cores and reveal a velocity and temperature gradient in the most massive core. We also find evidence of a bipolar outflow, possibly powered by a low-mass star. Conclusions. We present the tentative detection of a circumstellar self-gravitating disk lying in the most massive core and powering a large-scale outflow previously known in the literature. In our scenario, the star powering the flow is responsible for most of the luminosity of IRAS 23385+6053 (~3000 L⊙). The other cores, albeit with masses below the corresponding virial masses, appear to be accreting material from their molecular surroundings and are possibly collapsing or on the verge of collapse. We conclude that we are observing a sample of star-forming cores that is bound to turn into a cluster of massive stars.