EXPLORING IO'S ATMOSPHERIC COMPOSITION WITH APEX: FIRST MEASUREMENT OF 34SO2 AND TENTATIVE DETECTION OF KCl
EXPLORING IO'S ATMOSPHERIC COMPOSITION WITH APEX: FIRST MEASUREMENT OF 34SO2 AND TENTATIVE DETECTION OF KCl
复制标题
用 APEX 探索 IO 的大气成分：首次测量 34SO2 并初步检测到 KCl
DOI：
10.1088/0004-637x/776/1/32
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
B. Butler
中科院分区：
文献类型：
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作者：
A. Moullet;E. Lellouch;R. Moreno;M. Gurwell;J. Black;B. Butler
木卫一稀薄的大气层的组成没有受到严格的限制。只有主要物质SO2和少数次要物质已被确定，但根据火山气体化学的热化学平衡模型和木卫一环境的组成，应该存在多种其他分子物质。本文主要研究未被发现的分子物种（KCl，SiO，S2 O）和同位素（34 SO2）的光谱搜索。我们分析了磁盘平均频谱的潜在线丰富的频谱窗口约345 GHz，在2010年获得的APEX 12米天线。使用不同的模型，假设扩展的大气分布或纯粹的火山维持的大气，我们尝试测量KCl相对于SO2的相对丰度，并得出范围为4 × 10−4-8 × 10−3。我们没有检测到SiO或S2 O，并提出了新的上限，其丰度。我们还提出了第一次测量的34 S/32 S同位素比在气相中的木卫一，这似乎是地球和星际介质的参考值的两倍。还分析了SO2和SO的强线，以检查柱密度和相对丰度的纵向变化。我们的模型表明，根据其预测的相对丰度相对于SO2在火山羽流，无论是试探性的KCl检测和SiO上限是兼容的纯火山起源这些物种。
The composition of Io's tenuous atmosphere is poorly constrained. Only the major species SO2 and a handful of minor species have been positively identified, but a variety of other molecular species should be present, based on thermochemical equilibrium models of volcanic gas chemistry and the composition of Io's environment. This paper focuses on the spectral search for expected yet undetected molecular species (KCl, SiO, S2O) and isotopes (34SO2). We analyze a disk-averaged spectrum of a potentially line-rich spectral window around 345 GHz, obtained in 2010 at the APEX 12 m antenna. Using different models assuming either extended atmospheric distributions or a purely volcanically sustained atmosphere, we tentatively measure the KCl relative abundance with respect to SO2 and derive a range of 4 × 10−4–8 × 10−3. We do not detect SiO or S2O and present new upper limits on their abundances. We also present the first measurement of the 34S/32S isotopic ratio in gas phase on Io, which appears to be twice as high as the Earth and interstellar medium reference values. Strong lines of SO2 and SO are also analyzed to check for longitudinal variations of column density and relative abundance. Our models show that, based on their predicted relative abundance with respect to SO2 in volcanic plumes, both the tentative KCl detection and SiO upper limit are compatible with a purely volcanic origin for these species.