我们构建了气体-颗粒化学网络模型，其中包括碳同位素（12 C和13 C），重点是同位素交换反应。通过数值计算，研究了冷密云核中CCH和CCS的分子丰度、碳同位素比值（12 CX/13 CX）和同位素异构体比值（12 C 13 CX/13 C 12 CX）的时间变化。我们确认，无论是在气相和晶粒表面的分子的同位素比，是显着不同的取决于分子是由碳原子（离子）或CO分子。由碳原子形成的分子具有大于[12 C/13 C]的元素丰度比的CX/13 CX比。另一方面，由CO分子形成的分子具有小于[12 C/13 C]比的CX/13 CX比。如果同位素异构体交换反应13 CCH + H C13 CH <->+ H + 8.1 K进行时正向速率系数kf > 10^-11 cm 3 s-1，我们重现了在TMC-1中观测到的C13 CH/13 CCH比值。然而，C13 CS/13 CCS比低于TMC-1中观察到的比例。然后我们假设H原子催化的同位素异构体交换反应，13 CCS + H <->C13 CS + H + 17.4 K。在此反应模型中，我们同时重现了所观察到的C13 CS/13 CCS、CCS/C13 CS和CCS/13 CCS比率。
英文摘要：
We construct the gas-grain chemical network model which includes carbon isotopes (12C and 13C) with an emphasis on isotopomer-exchange reactions. Temporal variations of molecular abundances, the carbon isotope ratios (12CX/13CX) and the isotopomer ratios (12C13CX/13C12CX) of CCH and CCS in cold dense cloud cores are investigated by numerical calculations. We confirm that the isotope ratios of molecules, both in the gas phase and grain surfaces, are significantly different depending on whether the molecule is formed from the carbon atom (ion) or the CO molecule. Molecules formed from carbon atoms have the CX/13CX ratios greater than the elemental abundance ratio of [12C/13C]. On the other hand, molecules formed from CO molecules have the CX/13CX ratios smaller than the [12C/13C] ratio. We reproduce the observed C13CH/13CCH ratio in TMC-1, if the isotopomer exchange reaction, 13CCH + H <-> C13CH + H + 8.1 K, proceeds with the forward rate coefficient kf > 10^-11 cm3 s-1. However, the C13CS/13CCS ratio is lower than that observed in TMC-1. We then assume the isotopomer exchange reaction catalyzed by the H atom, 13CCS + H <-> C13CS + H + 17.4 K. In the model with this reaction, we reproduce the observed C13CS/13CCS, CCS/C13CS and CCS/13CCS ratio simultaneously.
Isotopomer-Specific Carbon Isotope Ratio of Complex Organic Molecules in Star-Forming Cores
National Astronomical Observatory of Japan（日本国立天文台）；The Graduate University for Advanced Studies, SOKENDAI（综合研究大学院大学）；RIKEN Cluster for Pioneering Research（理化学研究所前沿研究集群）；The University of Tokyo（东京大学）；Queen’s University Belfast（贝尔法斯特女王大学）
A tale of two isotopes: Spatial variation in HCN fractionation toward young cores
Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）；Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心（CAB），西班牙国家科学研究委员会-国家航空技术研究所）；European Southern Observatory（欧洲南方天文台）
H$_2^{18}$O in the terrestrial planet-forming regions of protoplanetary disks
Vassar College（瓦萨学院）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Division of Geological and Planetary Sciences, California Institute of Technology（加州理工学院地质与行星科学系）；Department of Astronomy, University of Wisconsin-Madison（威斯康星大学麦迪逊分校天文学系）；Center for Astrophysics, Harvard & Smithsonian（哈佛-史密森尼天体物理中心）；Department of Physics, Texas State University（德克萨斯州立大学物理系）；Weber State University（韦伯州立大学）；Department of Astronomy, University of Michigan（密歇根大学天文学系）；Astrophysics & Space Institute, Schmidt Sciences（施密特科学天体物理学与空间研究所）；Department of Physics and Astronomy, University of Exeter（埃克塞特大学物理与天文系）；Department of Astronomy, University of Maryland（马里兰大学天文学系）
High $^{12}$C/$^{13}$C isotopic ratios toward G+0.693-0.027: evidence for gas inflow to the Central Molecular Zone
Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心）；Max-Planck-Institut für Extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）；European Southern Observatory（欧洲南方天文台）；Joint ALMA Observatory（ALMA联合天文台）；Star and Planet Formation Laboratory, Cluster for Pioneering Research, RIKEN（理化学研究所前沿研究集群恒星与行星形成实验室）
