Spectroscopic mapping of Io's surface with HST/STIS: SO${}_2$ frost, sulfur allotropes, and large-scale compositional patterns

Abstract

Io's intense volcanic activity results in one of the most colorful surfaces in the solar system. Ultraviolet and visible-wavelength observations of Io are critical to uncovering the chemistry behind its volcanic hues. Here, we present global, spatially resolved UV-visible spectra of Io from the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST), which bridge the gap between previous highly resolved imagery and disk-integrated spectroscopy, to provide an unprecedented combination of spatial and spectral detail. We use this comprehensive dataset to investigate spectral endmembers, map observed spectral features associated with SO${}_2$ frost and other sulfur species, and explore possible compositions in the context of Io surface processes. In agreement with past observations, our results are consistent with extensive equatorial SO${}_2$ frost deposits that are stable over multi-decade timescales, widespread sulfur-rich plains surrounding the SO${}_2$ deposits, and the enrichment of Pele's pyroclastic ring and the high-latitude regions in metastable short-chain sulfur allotropes.

15 pages, 8 figures, published in PSJ

References in corpus (4)

• Io's Volcanic Activity from Time Domain Adaptive Optics Observations: 2013-2018
• Detection and characterization of Io's atmosphere from high-resolution 4-μm spectroscopy
• High Spatial and Spectral Resolution Observations of the Forbidden 1.707 micron Rovibronic SO Emissions on Io: Evidence for Widespread Stealth Volcanism
• Endogenic and Exogenic Contributions to Visible-wavelength Spectra of Europa's Trailing Hemisphere

Cited by in corpus (2)

• Spectroscopic Mapping of Callisto with HST/STIS and Implications for its Surface Composition
• Modeling Volcanic Plume Heights Across Exoplanet Atmospheres: Insights from TRAPPIST-1