Anomalous Nitrogen Isotope Ratio in Comets
Anomalous Nitrogen Isotope Ratio in Comets
复制标题
彗星中异常的氮同位素比
作者：
C. Arpigny;E. Jehin;J. Manfroid;D. Hutsemékers;R. Schulz;J. Stüwe;J. Zucconi;I. Ilyin
CN B2 ∑+-X2 ∑+（0，0）波段在390纳米处的高分辨率光谱给出了C/1995 O 1（海尔-波普彗星）和C/2000 WM 1（线性彗星）的同位素比值如下：12 C/13 C为165 ± 40和115 ± 20，14 N/15 N为140 ± 35和140 ± 30。我们的N同位素测量值低于陆地的14 N/15 N = 272和来自HCN测量的Hale-Bopp的比值，HCN是CN的假定亲种。这种同位素异常表明存在氯化萘的其他母体，其氮同位素比率甚至更低。像在行星际尘埃颗粒中发现的有机化合物是很好的候选者。
High-resolution spectra of the CN B2 ∑+–X2 ∑+ (0,0) band at 390 nanometers yield isotopic ratios for comets C/1995 O1 (Hale-Bopp) and C/2000 WM1 (LINEAR) as follows: 165 ± 40 and 115 ± 20 for 12C/13C, 140 ± 35 and 140 ± 30 for 14N/15N. Our N isotopic measurements are lower than the terrestrial 14N/15N = 272 and the ratio for Hale-Bopp from measurements of HCN, the presumed parent species of CN. This isotopic anomaly suggests the existence of other parent(s) of CN, with an even lower N isotopic ratio. Organic compounds like those found in interplanetary dust particles are good candidates.