How to identify the youngest protostars
How to identify the youngest protostars
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如何识别最年轻的原恒星
DOI：
10.1051/0004-6361:20052952
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发表时间：
2005
影响因子：
6.5
通讯作者：
S. Goodwin
中科院分区：
文献类型：
--
作者：
D. Stamatellos;A. Whitworth;D. Boyd;S. Goodwin
我们研究了从星前核到0类原恒星的过渡，使用SPH来模拟动力学演化，并使用Monte Carlo辐射传输代码来生成SED和等照度图。对于标准星际辐射场照明的星前核，亮度较低，SED峰值约为190 μ m。一旦原恒星形成，光度上升（由于吸积作用对原恒星的贡献越来越大），SED的峰值向更短的波长移动（80~100 μ m）。然而，在0级阶段结束时，吸积率下降，光度下降，SED的峰值向更长的波长（90至150 μ m）移动。在我们的模拟中，原恒星周围的物质密度在0级阶段仍然足够高，只有当原恒星动态地从中心移位时，它才能在近红外中可见。原始submm/mm 0级原恒星的地图往往是更集中的凝聚比星前的核心。然而，当与典型的望远镜光束卷积时，中心浓度的差异不太明显，尽管0级原恒星看起来更圆。我们的研究结果表明，如果一个核心被认为是星前的基础上，没有相关的IRAS源，没有厘米射电发射，没有流出，但它有一个圆形的外观和SED的峰值波长低于170\，\mu {\rm}$，它很可能包含一个非常年轻的0级原恒星。
We study the transition from a prestellar core to a Class 0 protostar, using SPH to simulate the dynamical evolution, and a Monte Carlo radiative transfer code to generate the SED and isophotal maps. For a prestellar core illuminated by the standard interstellar radiation field, the luminosity is low and the SED peaks at ~ $190\,\mu {\rm m}$. Once a protostar has formed, the luminosity rises (due to a growing contribution from accretion onto the protostar) and the peak of the SED shifts to shorter wavelengths ( $80~{\rm to}\,100\,\mu {\rm m}$). However, by the end of the Class 0 phase, the accretion rate is falling, the luminosity has decreased, and the peak of the SED shifts back towards longer wavelengths ( $90\;{\rm to}\,150\,\mu {\rm m}$). In our simulations, the density of material around the protostar remains sufficiently high well into the Class 0 phase that the protostar only becomes visible in the NIR if it is displaced from the centre dynamically. Raw submm/mm maps of Class 0 protostars tend to be much more centrally condensed than those of prestellar cores. However, when convolved with a typical telescope beam, the difference in central concentration is less marked, although the Class 0 protostars appear more circular. Our results suggest that, if a core is deemed to be prestellar on the basis of having no associated IRAS source, no cm radio emission, and no outflow, but it has a circular appearance and an SED which peaks at wavelengths below ~ $170\,\mu {\rm m}$, it may well contain a very young Class 0 protostar.