EXPLORING IO'S ATMOSPHERIC COMPOSITION WITH APEX: FIRST MEASUREMENT OF (SO2)-S-34 AND TENTATIVE DETECTION OF KCl
Artikel i vetenskaplig tidskrift, 2013

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 ((SO2)-S-34). 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 x 10(-4)-8 x 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 S-34/S-32 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.

planets and satellites

planetary systems

submillimeter

atmospheres

Författare

A. Moullet

National Radio Astronomy Observatory

E. Lellouch

LESIA - Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique

R. Moreno

LESIA - Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique

M. Gurwell

Harvard-Smithsonian Center for Astrophysics

John H Black

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

B. Butler

National Radio Astronomy Observatory Socorro

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 776 32 (pp. 1-9) 32

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fundament

Grundläggande vetenskaper

Infrastruktur

Onsala rymdobservatorium

DOI

10.1088/0004-637x/776/1/32