Exploring an Evolution of Chemical Diversity from Protostellar disks to Protoplanetary disks

现在已经确定，低质量的0类原恒星源显示出显著的化学多样性。在这项研究中，进一步探索了这种多样性向原恒星盘和原行星盘的演化。用Nobeama 45m望远镜和IRAM30m望远镜对不同的I类源进行了谱线测量观测，确定TMC-1A是一种具有丰富碳链分子存在的WCCC(温碳链化学)源的I类类似物。同时，通过使用ALMA(阿塔卡马大毫米/亚毫米阵列)观测了具有1“或更高空间分辨率的原型L1527，研究了WCCC源的演化。碳链分子被证实存在于内径约为100AU的内径约为100AU的旋转包络中，尽管其中缺乏碳链分子。这是了解WCCC源化学演化的重要线索。此外，为了探索WCCC现象的起源，利用德国马克斯·普朗克研究所100m望远镜观测到了金牛座分子云中海尔斯云2上CH的大尺度分布。在这一结果的基础上，我批判性地测试了一种可能性，即母云中短时间尺度的恒星形成是造成WCCC现象的原因。

It is now established that low-mass Class 0 protostellar sources show significant chemical diversity. In this study, further evolution of such diversity toward protostellar disks and protoplanetary disks has been explored. Spectral line survey observations have been conducted toward various Class I sources with the Nobeyama 45 m telescope and the IRAM30 m telescope, and TMC-1A has been identified as a Class I analog of the WCCC (warm carbon chain chemistry) source which is characterized by rich existence of carbon-chain molecules. In parallel, the evolution of the WCCC source has been studied by observing its prototype, L1527, with high spatial resolution of 1” or better by using ALMA (Atacama Large Millimeter/submillimeter Array). Carbon-chain molecules are confirmed to exist inan infalling rotating envelope whose inner radius is about 100 AU, although they are deficient within it. This is an important clue to an understanding chemical evolution of the WCCC sources. Furthermore, large scale distribution of CH has been observed toward Heiles Cloud 2 in the Taurus molecular cloud by using the Max Planck Institute 100 m telescope in Germany in order to explore an origin of the WCCC phenomenon. On the basis of the result, I have critically tested a possibility that short timescale of star-formation in a parent cloud is responsible for the WCCC phenomenon.