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arXiv 0705.1427astro-ph
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南半球Re 4 IRS - HH 188区分子发射的起源

The origin of the molecular emission around the southern hemisphere Re 4 IRS - HH 188 region

J. M. Girart, S. Viti

摘要:

我们目前SEST观测的分子环境的南部赫比格-哈罗对象188(HH 188),与低质量的原恒星Re 4 IRS。我们还使用了SuperCosmos Halalpha巡天来寻找与Re 4 IRS-HH 188区域相关的Halalpha发射。目前工作的目的是研究分子气体的性质,并更好地描述这个南部恒星形成区。我们绘制了YSO周围的HCO+ 3-2和H13 CO + 1-0发射图,并拍摄了朝向中心源的CH 3OH 2(0)-1(0)A+和2(-1)-1(-1)E和SO 6(5)-5(4)的光谱。列密度推导和不同的情况下被认为是解释的分子发射的起源。HCO+产生于YSO周围一个相对紧凑的区域;然而,它的峰值发射沿着外流方向向南移动。我们的化学分析表明,一个合理的情况是,大部分的排放来自HH 188物体前面的冷的、被照亮的致密气体。我们还发现,HH 188,一个高激发天体,似乎是一个秒差距尺度和高度准直HH系统的一部分。Re 4 IRS可能是一个二元原恒星系统,处于0类或I类相位晚期。其中一颗在近红外波段看不见的原恒星似乎为HH 188系统提供了动力。

英文摘要:

We present SEST observations of the molecular environment ahead of the southern Herbig-Haro object 188 (HH188), associated with the low-mass protostar Re4 IRS. We have also used the SuperCosmos Halpha survey to search for Halpha emission associated with the Re4 IRS - HH188 region. The aim of the present work is to study the properties of the molecular gas and to better characterize this southern star forming region. We mapped the HCO+ 3-2 and H13CO+ 1-0 emission around the YSO and took spectra of the CH3OH 2(0)-1(0)A+ and 2(-1)-1(-1)E and SO 6(5)-5(4) towards the central source. Column densities are derived and different scenarios are considered to explain the origin of the molecular emission. HCO+ arises from a relatively compact region around the YSO; however, its peak emission is displaced to the south following the outflow direction. Our chemical analysis indicates that a plausible scenario is that most of the emission arises from the cold, illuminated dense gas ahead of the HH188 object. We have also found that HH188, a high excitation object, seems to be part of a parsec scale and highly collimated HH system. Re4 IRS is probably a binary protostellar system, in the late Class 0 or Class I phase. One of the protostars, invisible in the near-IR, seems to power the HH188 system.

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