Observations with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope have been used to constrain the atomic sulfur column density in Io's atmosphere. The S I λ1479 dipole allowed and forbidden transition multiplets have been resolved for the first time at Io, enabling the study of both optically thick and thin transitions from a single atomic species. The allowed transitions contribute 62% ± 8% and the forbidden transitions 38% ± 8%, on average, to the total signal of the S I λ1479 multiplets. Using the optically thick and thin transitions of S I λ1479 observed near the limbs of Io, we derive a tangential atmospheric sulfur column abundance of 3.6 × 1012 cm-2 NS 1.7 × 1013 cm-2, which is independent of electron temperature and density. A low-density SO2 atmosphere, NSO2 ~ (5–10) × 1015 cm-2, consistent with that inferred from other recent observations, is most consistent with these bounds.
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机译：哈勃太空望远镜上的太空望远镜成像光谱仪进行的观测已被用来限制艾奥大气中原子硫柱的密度。 S Iλ1479偶极子允许和禁止的跃迁多重峰已在Io上首次得到解决，从而使得能够研究单个原子物种的光学跃迁和薄跃迁。平均而言，允许的跃迁对S Iλ1479多重信号的总信号贡献62％±8％，而禁止的跃迁贡献38％±8％。利用在Io的四肢附近观察到的SIλ1479的光学上的粗细过渡，我们得出了一个正切的大气硫柱丰度为3.6×1012 cm-2 展开▼
