Jupiter in the Ultraviolet: Acetylene and Ethane Abundances in the Stratosphere of Jupiter from Cassini Observations between 0.15 and 0.19 μm

Journal Article · Mon Jun 01 04:00:00 EDT 2020 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/AB91A6· OSTI ID:23013247

Melin, Henrik; Fletcher, L. N. ^[1]; Irwin, P. G. J. ^[2]

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1. School of Physics & Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
2. University of Oxford (United Kingdom)

At wavelengths between 0.15 and 0.19 μm, the far-ultraviolet spectrum of Jupiter is dominated by the scattered solar spectrum, attenuated by molecular absorptions primarily by acetylene and ethane, and to a lesser extent ammonia and phosphine. We describe the development of our radiative transfer code that enables the retrieval of abundances of these molecular species from ultraviolet reflectance spectra. As a proof-of-concept we present an analysis of Cassini Ultraviolet Imaging Spectrograph (UVIS) observations of the disk of Jupiter during the 2000/2001 flyby. The ultraviolet-retrieved acetylene abundances in the upper stratosphere are lower than those predicted by models based solely on infrared thermal emission from the mid-stratosphere observed by the Composite Infrared Spectrometer (CIRS), requiring an adjustment to the vertical profiles above 1 mbar. We produce a vertical acetylene abundance profile that is compatible with both CIRS and UVIS, with reduced abundances at pressures <1 mbar: the 0.1 mbar abundances are 1.21 ± 0.07 ppm for acetylene and 20.8 ± 5.1 ppm for ethane. Finally, we perform a sensitivity study for the JUICE ultraviolet spectrograph, which has extended wavelength coverage out to 0.21 μm, enabling the retrieval of ammonia and phosphine abundances, in addition to acetylene and ethane.

• OSTI ID: 23013247
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 6 Vol. 159; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ACETYLENE
AMMONIA
ELEMENT ABUNDANCE
EMISSION
ETHANE
FAR ULTRAVIOLET RADIATION
INFRARED SPECTROMETERS
JUPITER PLANET
PHOSPHINES
PLANETARY ATMOSPHERES
SPECTRA
STRATOSPHERE
WAVELENGTHS