Millimeter-wave observations of Io with the IRAM 30 m telescope have allowed the detection of two rotational lines of SO at 219.949 and 138.178 GHz in Io's atmosphere. The observations can be fitted by assuming that gaseous SO is collocated with SO, on a restricted fraction of Io's surface. In this case, the SO/SO_2 mixing ratio is 3%-10%, in agreement with predictions from one-dimensional photochemical models and suggesting a vertical eddy diffusion coefficient in the range 3 X 10~7 to 3 X 10~8 cm~2 s~(-1). Alternatively, SO could constitute a tenuous, global atmosphere with column density in the range (2-6) X 10~(14) cm~(-2). Photochemistry in SO_2 hydrostatic and/or volcanic plume atmospheres and horizontal transport can conceivably produce such an extended SO atmosphere.
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机译：使用IRAM 30 m望远镜对Io进行的毫米波观测已允许在Io大气中检测到219.949 GHz和138.178 GHz GHz的两条SO旋转线。可以通过假设气态SO与SO并置在Io表面的有限部分上来拟合这些观察结果。在这种情况下，SO / SO_2的混合比为3％-10％，与一维光化学模型的预测相符，并且表明垂直涡流扩散系数在3 X 10〜7到3 X 10〜8 cm〜的范围内2 s〜（-1）。或者，SO可以构成一种脆弱的全球大气，其柱密度在（2-6）X 10〜（14）cm〜（-2）范围内。可以想象，在SO_2流体静压和/或火山羽流气氛中进行光化学反应和水平传输可以产生这种扩展的SO气氛。
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