大质量恒星形成区W51 North区域的物理和化学环境
发布时间:2018-02-16 09:20
本文关键词: W51 North 分子线 大质量恒星 出处:《云南大学》2016年硕士论文 论文类型:学位论文
【摘要】:在本文中,我们报道了亚毫米波干涉阵(SMA)对大质量恒星形成区W51North区域的观测结果,得到了两个边带的分子谱线,其频率范围分别是216.5 GHz到217.5 GHz(下边带)和226.5 GHz至228.5 GHz(上边带)。基于观测数据,我们运用XCLASS软件证认了这些跃迁来自于17个分子品种(包括同位素分子),这些分子品种包括了含氧分子,含氮分子,含硫分子和含重氢分子。我们证认了13个丙酮分子((CH3)2CO)的跃迁,证认了W51 North是银河系中第三个发现丙酮分子的天体。从分子气体分布看,这些分子的分布在其峰值位置周围呈现出比较致密的特征,而且它们峰值位置与连续谱峰值位置一致,含氧和含氮分子在分布上并没有明显差异。在局部热动平衡的假设下,我们使用了XCLASS软件估算了这些分子的柱密度和转动温度,结果表明,含氧分子的柱密度(4.3×1016到2.3×1018 cm-2)比含氮分子要高(2.8×1015到2.6×1016 cm-2)。所有分子的转动温度都在100—200 K的范围内,这表明,这些分子起源于一个温暖的天体物理环境。根据连续谱的信息,我们计算得到了H2的柱密度为6.4×1024cm-2,并计算了所有分子相对于H2的丰度。结果表明相比于含氮分子,含氧分子拥有较高的丰度。最后,基于这些分子的气体分布、丰度和转动温度、我们推测这些来自W51 North的分子所产生的环境是一个氮和氧混合得很好的热核。
[Abstract]:In this paper, we report the observation results of the large mass star formation region W51 North by submillimeter wave interference array (SMA). The molecular spectral lines of two sideband are obtained. Their frequency ranges are 216.5 GHz to 217.5 GHz (lower sideband) and 226.5 GHz to 228.5 GHz (upper sideband). We used the XCLASS software to identify that these transitions came from 17 molecular species (including isotopic molecules, including oxygen molecules, nitrogen molecules, We have identified the transition of 13 acetone molecules, Ch _ 3H _ 2CO) and that W51 North is the third object in the Milky way to find acetone molecules. The distribution of these molecules is dense around their peak position, and their peak position is consistent with the peak position of continuous spectrum. There is no significant difference in the distribution of oxygen and nitrogen molecules. Under the assumption of local thermodynamic equilibrium, We use XCLASS software to estimate the column density and rotation temperature of these molecules. The results show that the column densities of oxygen molecules are 4.3 脳 1016 to 2.3 脳 1018 cm-2) higher than that of nitrogen-containing molecules. The rotation temperatures of all molecules are in the range of 100-200K. These molecules originated in a warm astrophysical environment. Based on the information of the continuous spectra, we calculated the column density of H2 is 6.4 脳 1024cm-2, and calculated the abundance of all the molecules relative to H2. Finally, based on the gas distribution, abundance and rotation temperature of these molecules, we speculate that the environment produced by these molecules from W51 North is a hot nucleus with a good mixture of nitrogen and oxygen.
【学位授予单位】:云南大学
【学位级别】:硕士
【学位授予年份】:2016
【分类号】:P144;P148
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本文编号:1515182
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