Molecular investigations of comets C/2002 X5 (Kudo-Fujikawa), C/2002 V1 (NEAT), and C/2006 P1 (McNaught) at small heliocentric distances
Molecular investigations of comets C/2002 X5 (Kudo-Fujikawa), C/2002 V1 (NEAT), and C/2006 P1 (McNaught) at small heliocentric distances
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DOI：
10.1051/0004-6361/201016250
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发表时间：
2011-02
影响因子：
6.5
通讯作者：
N. Biver;D. Bockel'ee-Morvan;P. Colom;J. Crovisier;G. Paubert;A. Weiss;H. Wiesemeyer
中科院分区：
文献类型：
--
作者：
N. Biver;D. Bockel'ee-Morvan;P. Colom;J. Crovisier;G. Paubert;A. Weiss;H. Wiesemeyer
我们展示了对彗星 C/2002 X5 (Kudo-Fujikawa)、C/2002 VI (NEAT) 和 C/2006 P1 (McNaught) 的独特光谱射电观测，这些彗星在 2003 年和 2007 年位于太阳 r h ≈ 0.2 AU 范围内。当这些彗星被观测到时，在每颗彗星中都检测到了分子 OH、HCN、HNC、CS 和 CH 3 OH。暴露于太阳的强烈加热下。分别在彗星C/2002 X5和C/2006 PI中检测到HC 3 N和HCO + 。我们表明，在这些靠近太阳的非常多产的彗星中，太阳紫外线辐射的光解作用起着不可忽视的作用。还测量并模拟了气体膨胀速度的加速度和昼夜不对称性。当 r h = I AU 时，CS 光解离寿命被限制为约 2.5 x 10 ―5 s ―1 。将相对丰度与通过更遥远的 C/2002 X5 或其他彗星观测确定的值进行比较。测量到距太阳 0.5 至 0.1 天文单位之间的 HNC/HCN 生产率较高，范围为 10-30%。彗星彗发中 CS 显着富集的趋势 (CS/HCN ∝ r ―0.8 h ) 在所有三颗彗星中均得到证实。 CH 3 OH/HCN产率比在低r h 下降低。 C/2002 X5 彗星中的 HC 3 N/HCN 生产率比是任何其他彗星中测得的四倍。
We present unique spectroscopic radio observations of comets C/2002 X5 (Kudo-Fujikawa), C/2002 VI (NEAT), and C/2006 P1 (McNaught), which came within r h ≈ 0.2 AU of the Sun in 2003 and 2007. The molecules OH, HCN, HNC, CS, and CH 3 OH were detected in each of these comets when they were exposed to strong heating from the Sun. HC 3 N and HCO + were detected in comets C/2002 X5 and C/2006 PI, respectively. We show that in these very productive comets close to the Sun screening of the photodissociation by the Sun UV radiation plays a non-negligible role. Acceleration of the gas expansion velocity and day-night asymmetry is also measured and modeled. The CS photodissociation lifetime was constrained to be about 2.5 x 10 ―5 s ―1 at r h = I AU. The relative abundances are compared to values determined from more distant observations of C/2002 X5 or other comets. A high HNC/HCN production-rate ratio, in the range 10-30% between 0.5 and 0.1 AU from the Sun, is measured. The trend for a significant enrichment in CS in cometary comae (CS/HCN ∝ r ―0.8 h ) is confirmed in all three comets. The CH 3 OH/HCN production rate ratio decreases at low r h . The HC 3 N/HCN production rate ratio in comet C/2002 X5 is four times higher than measured in any other comet.