Mumma M J, DiSanti M A, Dello Russo N, Fomenkova M, Magee-Sauer K, Kaminski C D, Xie D X
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
Science. 1996 May 31;272(5266):1310-4. doi: 10.1126/science.272.5266.1310.
The saturated hydrocarbons ethane (C2H6) and methane (CH4) along with carbon monoxide (CO) and water (H2O) were detected in comet C/1996 B2 Hyakutake with the use of high-resolution infrared spectroscopy at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii. The inferred production rates of molecular gases from the icy, cometary nucleus (in molecules per second) are 6.4 X 10(26) for C2H6, 1.2 X 10(27) for CH4, 9.8 X 10(27) for CO, and 1.7 X 10(29) for H2O. An abundance of C2H6 comparable to that of CH4 implies that ices in C/1996 B2 Hyakutake did not originate in a thermochemically equilibrated region of the solar nebula. The abundances are consistent with a kinetically controlled production process, but production of C2H6 by gas-phase ion molecule reactions in the natal cloud core is energetically forbidden. The high C2H6/CH4 ratio is consistent with production of C2H6 in icy grain mantles in the natal cloud, either by photolysis of CH4-rich ice or by hydrogen-addition reactions to acetylene condensed from the gas phase.
利用位于夏威夷莫纳克亚山上的美国国家航空航天局红外望远镜设施的高分辨率红外光谱，在彗星C/1996 B2百武彗星中检测到了饱和烃乙烷（C₂H₆）和甲烷（CH₄）以及一氧化碳（CO）和水（H₂O）。从彗星冰核推断出的分子气体产生率（每秒分子数）分别为：乙烷6.4×10²⁶、甲烷1.2×10²⁷、一氧化碳9.8×10²⁷、水1.7×10²⁹。乙烷与甲烷的丰度相当，这意味着C/1996 B2百武彗星中的冰并非起源于太阳星云的热化学平衡区域。这些丰度与动力学控制的产生过程一致，但在原恒星云核中通过气相离子分子反应产生乙烷在能量上是被禁止的。高的乙烷/甲烷比值与原恒星云中冰粒幔层中乙烷的产生一致，这要么是通过富含甲烷的冰的光解，要么是通过对从气相冷凝的乙炔进行加氢反应。
