An Unbiased Spectral Line Survey toward R CrA IRS7B in the 345 GHz Window with ASTE
An Unbiased Spectral Line Survey toward R CrA IRS7B in the 345 GHz Window with ASTE
复制标题
使用 ASTE 在 345 GHz 窗口中对 R CrA IRS7B 进行无偏谱线测量
DOI：
10.1088/0004-637x/745/2/126
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
and S. Yamamoto
中科院分区：
文献类型：
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作者：
Y. Watanabe;N. Sakai;J.E. Lindberg;J.K. Jorgensen;S. E. Bisschop;and S. Yamamoto
我们已经进行了光谱线调查，在332-364 GHz的区域与阿塔卡马亚毫米望远镜实验10米望远镜对R CrA IRS 7 B，一个低质量的原恒星在0类或0/I类过渡阶段。我们还在450 GHz频段进行了一些补充观测。在332-364 GHz区域总共鉴定了16种分子物种。CN和CCH的强发射线被观察到，而复杂的有机分子和长碳链分子，这是热corino和暖碳链化学（WCCC）源的特征，分别没有被检测到。CH 3 OH的旋转温度为31 K，明显低于原型热Corino IRAS 16293-2422的旋转温度（约85 K）.计算得到CCH和H2 CO的氘分馏比分别为0.038和0.050，远低于热科里诺的氘分馏比。这些结果表明在R CrA IRS 7 B中存在弱的热corino活性。另一方面，发现与碳链相关的分子CCH和cC 3 H2是丰富的。然而，这种来源不能归类为WCCC来源，因为没有检测到长碳链分子。如果WCCC和热可里诺化学代表了低质量0级源化学成分的两个极端，那么R CrA IRS 7 B将是具有这两种化学特征的混合物。来自附近赫比格Ae星星R CrA的紫外线辐射也可能影响其化学成分。目前的线调查表明，在低质量恒星形成区进一步的化学多样性。
We have conducted a spectral line survey in the 332–364 GHz region with the Atacama Submillimeter Telescope Experiment 10 m telescope toward R CrA IRS7B, a low-mass protostar in the Class 0 or Class 0/I transitional stage. We have also performed some supplementary observations in the 450 GHz band. In total, 16 molecular species are identified in the 332–364 GHz region. Strong emission lines of CN and CCH are observed, whereas complex organic molecules and long carbon-chain molecules, which are characteristics of hot corino and warm carbon-chain chemistry (WCCC) source, respectively, are not detected. The rotation temperature of CH 3 OH is evaluated to be 31 K, which is significantly lower than that reported for the prototypical hot corino IRAS 16293-2422 (∼ 85 K). The deuterium fractionation ratios for CCH and H 2 CO are obtained to be 0.038 and 0.050, respectively, which are much lower than those in the hot corino. These results suggest a weak hot corino activity in R CrA IRS7B. On the other hand, the carbon-chain related molecules, CCH and cC 3 H 2, are found to be abundant. However, this source cannot be classified as a WCCC source, since long carbon-chain molecules are not detected. If WCCC and hot corino chemistry represent the two extremes in chemical compositions of low-mass Class 0 sources, R CrA IRS7B would be a source with a mixture of these two chemical characteristics. The UV radiation from the nearby Herbig Ae star R CrA may also affect the chemical composition. The present line survey demonstrates further chemical diversity in low-mass star-forming regions.