A SENSITIVE SEARCH FOR DEUTERATED WATER IN COMET 8P/TUTTLE
A SENSITIVE SEARCH FOR DEUTERATED WATER IN COMET 8P/TUTTLE
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对 COMET 8P/TUTTLE 中氘水的灵敏搜索
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Lippi
中科院分区：
文献类型：
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作者：
G. Villanueva;M. Mumma;B. Bonev;M. DiSanti;E. Gibb;H. Böhnhardt;M. Lippi
我们报告了一个敏感的搜索氘水（HDO）在彗星8 P/塔特尔使用高分辨率光谱在红外（IR）波长。彗星水的氘丰度是彗星最重要的宇宙起源指标之一。这个比率保留了彗星物质形成条件的信息，并测试了彗星在为地球海洋提供水方面的可能贡献。2008年1月27日至2008年2月3日，在智利Cerro Paranal山顶甚大望远镜天文台的8.2 m Antu望远镜上使用新的红外光谱仪（低温红外中阶梯光谱仪）对8 P/Tuttle彗星中的水（H2O）和HDO进行了采样。在3.7 μm附近对23条HDO线进行了采样，产生速率为4.73 ± 1.68 × 1025 s−1。将这个数值与H2O的产生速率5790 ± 250 × 1025 s−1结合起来，得到彗星8 P/Tuttle的正式数值= 4.09 ± 1.45 × 10−4。这个数值比维也纳标准平均海水大2.62 ± 0.93倍，与其他三颗奥尔特云彗星的浓缩系数相当。这里描述的技术提供了前所未有的灵敏度，最终使我们能够定期测量这一主要的宇宙起源指标，即使是在像8 P/塔特尔这样产气率相对较低的彗星中。
We report a sensitive search for deuterated water (HDO) in comet 8P/Tuttle using high-resolution spectroscopy at infrared (IR) wavelengths. The deuterium enrichment of cometary water is one of the most important cosmogonic indicators in comets. The ratio preserves information about the conditions under which comet material formed, and tests the possible contribution of comets in delivering water for Earth's oceans. Water (H2O) and HDO were sampled in comet 8P/Tuttle from 2008 January 27 to 2008 February 3 using the new IR spectrometer (Cryogenic Infrared Echelle Spectrograph) at the 8.2 m Antu telescope of the Very Large Telescope Observatory atop Cerro Paranal, Chile. Twenty-three lines of HDO were sampled near 3.7 μm, leading to a production rate of 4.73 ± 1.68 × 1025 s−1. Combining this value with the H2O production rate of 5790 ± 250 × 1025 s−1 provides a formal value of = 4.09 ± 1.45 × 10−4 in comet 8P/Tuttle. This value is larger by a factor of 2.62 ± 0.93 than Vienna Standard Mean Ocean Water, and is comparable to enrichment factors measured for three other Oort cloud comets. The technique described here provides unprecedented sensitivities, ultimately permitting us to routinely measure this prime cosmogonic indicator, even in comets having relatively modest gas production rate like 8P/Tuttle.