ALMA detection of acetone, disulfur monoxide, and carbon monoxide in the Jupiter volcanic moon Io

TL;DR

This study reports the first ALMA spectroscopic detection of acetone, disulfur monoxide, and carbon monoxide in Io's thin, volcanic atmosphere, revealing new insights into its composition and volcanic processes.

Contribution

First detection of these molecules in Io's atmosphere using ALMA, expanding understanding of its volcanic gas composition and chemical processes.

Findings

Detected acetone, disulfur monoxide, and carbon monoxide with high significance.

Quantified molecular column densities in Io's atmosphere.

Indicated photolysis of acetone as a source of CO.

Abstract

The extremely thin atmosphere of Jupiter's volcanic moon Io primarily consists of sulfur (S), sodium (Na), and oxygen (O) molecules that are controlled by the combination of the sublimation and volcanic outgasses. We present the first spectroscopic detection of the two rotational emission lines of acetone (CH$_{3}$COCH$_{3}$) and a single emission line of disulfur monoxide (S$_{2}$O), and carbon monoxide (CO) at frequency $\nu$ = 346.539, 346.667, 346.543, and 345.795 GHz respectively using the archival data of high-resolution Atacama Large Millimeter/Submillimeter Array (ALMA) interferometer with band 7 observation. All molecular species are detected with $\ge$5$\sigma$ statistical significance. Jupiter's moon Io is the most volcanically active body in the solar system with a very thin and spatially variable atmosphere. The volcanic gas CH$_{3}$COCH$_{3}$, S$_{2}$O, and CO are mainly coming from volcanic plumes. The statistical column density of CH$_{3}$COCH$_{3}$ line is N(CH$_{3}$COCH$_{3}$) = 3.18$\times$10$^{15}$ cm$^{-2}$ but for the cases of S$_{2}$O and CO, the column densities are N(S$_{2}$O) = 2.63$\times$10$^{16}$ cm$^{-2}$ and N(CO) = 5.27$\times$10$^{15}$ cm$^{-2}$ respectively. The carbon monoxide gas is mainly formed by the photolysis of the volcanic gas acetone.