FILAMENTARY STAR FORMATION: OBSERVING THE EVOLUTION TOWARD FLATTENED ENVELOPES
FILAMENTARY STAR FORMATION: OBSERVING THE EVOLUTION TOWARD FLATTENED ENVELOPES
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DOI：
10.1088/0004-637x/761/2/171
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发表时间：
2012-11
期刊：
影响因子：
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通讯作者：
Katherine Lee;L. Looney;D. Johnstone;J. Tobin
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作者：
Katherine Lee;L. Looney;D. Johnstone;J. Tobin
从大尺度分子云（几个秒差距）到围绕0级源（1000 Au到100.1秒差距）的小尺度拱星包层，丝状结构无处不在。特别是，赫歇尔空间天文台最近的观测强调了大尺度细丝（几个秒差距）和星星形成的重要性。0级源周围的小尺度扁平包层使人想起大尺度的丝状体。我们提出了一个观测派生的情况下，描述的核心和拱星信封形成过程的一部分，灯丝的演变，为恒星形成的星星。如果这种假设是正确的，那么在无星核中应该存在密度更高的小尺度平行结构（长度为0.1 pc），尽管迄今为止几乎所有的干涉仪都未能观测到这种结构。我们使用毫米波天文学研究组合阵列（CARMA）和阿塔卡马大型毫米/亚毫米波阵列（阿尔马）对L1157中已知的0级扁平包络进行建模，在星前阶段对灯丝进行合成观测。我们表明，合理的估计列密度通过扁平的信封，在3毫米波长的CARMA D阵列是无法检测到这样的结构，所以以前的研究不会检测到它们。然而，由于更合适的分辨率和灵敏度，可以使用3 mm处的CARMA D+E阵列和1 mm处的CARMA E阵列检测子结构。与CARMA结果相比，阿尔马还能够以其前所未有的灵敏度检测亚结构并详细显示结构。这种探测将证实新提出的非球形星星形成的范例。
Filamentary structures are ubiquitous from large-scale molecular clouds (a few parsecs) to small-scale circumstellar envelopes around Class 0 sources (∼1000 AU to ∼0.1 pc). In particular, recent observations with the Herschel Space Observatory emphasize the importance of large-scale filaments (a few parsecs) and star formation. The small-scale flattened envelopes around Class 0 sources are reminiscent of the large-scale filaments. We propose an observationally derived scenario for filamentary star formation that describes the evolution of filaments as part of the process for formation of cores and circumstellar envelopes. If such a scenario is correct, small-scale filamentary structures (0.1 pc in length) with higher densities embedded in starless cores should exist, although to date almost all the interferometers have failed to observe such structures. We perform synthetic observations of filaments at the prestellar stage by modeling the known Class 0 flattened envelope in L1157 using both the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the Atacama Large Millimeter/Submillimeter Array (ALMA). We show that with reasonable estimates for the column density through the flattened envelope, the CARMA D array at 3 mm wavelengths is not able to detect such filamentary structure, so previous studies would not have detected them. However, the substructures may be detected with the CARMA D+E array at 3 mm and the CARMA E array at 1 mm as a result of more appropriate resolution and sensitivity. ALMA is also capable of detecting the substructures and showing the structures in detail compared to the CARMA results with its unprecedented sensitivity. Such detection will confirm the new proposed paradigm of non-spherical star formation.