Protostellar Evolution in Serpens Main: Possible Origin of Disk-size Diversity
Protostellar Evolution in Serpens Main: Possible Origin of Disk-size Diversity
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DOI：
10.3847/1538-4357/ab5284
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
Yusuke Aso;N. Hirano;Y. Aikawa;M. Machida;N. Ohashi;M. Saito;S. Takakuwa;Hsi-Wei Yen;Jonathan P. Williams
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文献类型：
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作者：
Yusuke Aso;N. Hirano;Y. Aikawa;M. Machida;N. Ohashi;M. Saito;S. Takakuwa;Hsi-Wei Yen;Jonathan P. Williams
我们利用阿塔卡马大型毫米波/亚毫米波阵列在1.3毫米连续谱线（12CO J = 2−1,SO JN = 65−54,C18O J = 2−1）的周期3观测到形成恒星的星团Serpens Main中的亚毫米连续凝聚SMM2、SMM4、SMM9和SMM11，其角分辨率为~ 0。″55 （240 au）。在1.3 mm连续体中检测到16个源，可分为三类。第1组由6个源组成，显示扩展连续发射和双极/单极12CO流出。虽然所有的第1群成员都被归类为0类原恒星，但我们的观测结果从12CO流出动力时间、SO发射分布、C18O分数丰度和连续体形态等方面揭示了它们之间的演化趋势。第2组由四个源组成，这些源与连续的丝状结构有关，没有12CO流出。从1.3 mm连续体强度估计的中心密度表明它们是处于金斯不稳定状态的恒星前源。第3组由6个斯皮策源组成，显示出点状的1.3 mm连续发射和块状的12CO流出。第3组的这些特征表明包络耗散，阻止了圆盘从目前的大小（r > 60 au）增长。第3组的成员是原恒星，可能是金牛座T星的前身，它们与最近的调查中发现的半径为几十个天文单位的小圆盘有关。
We have observed the submillimeter continuum condensations SMM2, SMM4, SMM9, and SMM11 in the star-forming cluster Serpens Main using the Atacama Large Millimeter/submillimeter Array during Cycle 3 in the 1.3 mm continuum, 12CO J = 2 − 1, SO JN = 65 − 54, and C18O J = 2 − 1 lines at an angular resolution of ∼0.″55 (240 au). Sixteen sources have been detected in the 1.3 mm continuum, which can be classified into three groups. Group 1 consists of six sources showing extended continuum emission and bipolar/monopolar 12CO outflows. Although all the Group 1 members are classified as Class 0 protostars, our observations suggest evolutionary trends among them in terms of 12CO outflow dynamical time, SO emission distribution, C18O fractional abundance, and continuum morphology. Group 2 consists of four sources associated with a continuum filamentary structure and no 12CO outflows. Central densities estimated from the 1.3 mm continuum intensity suggest that they are prestellar sources in a marginally Jeans unstable state. Group 3 consists of six Spitzer sources showing point-like 1.3 mm continuum emission and clumpy 12CO outflows. These features of Group 3 suggest envelope dissipation, preventing disk growth from the present size, r ≲ 60 au. The Group 3 members are protostars that may be precursors to the T Tauri stars associated with small disks at radii, of tens of astronomical units, identified in recent surveys.