Production of Sulfur Allotropes in Electron Irradiated Jupiter Trojans Ice Analogs

Journal Article · Sun Sep 10 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA85E0· OSTI ID:22679858

Mahjoub, Ahmed; Poston, Michael J.; Blacksberg, Jordana; Ehlmann, Bethany L.; Hodyss, Robert; Hand, Kevin P.; Carlson, Robert; Choukroun, Mathieu ^[1]; Eiler, John M.

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1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

In this paper, we investigate sulfur chemistry in laboratory analogs of Jupiter Trojans and Kuiper Belt Objects (KBOs). Electron irradiation experiments of CH{sub 3}OH–NH{sub 3}–H{sub 2}O and H{sub 2}S–CH{sub 3}OH–NH{sub 3}–H{sub 2}O ices were conducted to better understand the chemical differences between primordial planetesimals inside and outside the sublimation line of H{sub 2}S. The main goal of this work is to test the chemical plausibility of the hypothesis correlating the color bimodality in Jupiter Trojans with sulfur chemistry in the incipient solar system. Temperature programmed desorption (TPD) of the irradiated mixtures allows the detection of small sulfur allotropes (S{sub 3} and S{sub 4}) after the irradiation of H{sub 2}S containing ice mixtures. These small, red polymers are metastable and could polymerize further under thermal processing and irradiation, producing larger sulfur polymers (mainly S{sub 8}) that are spectroscopically neutral at wavelengths above 500 nm. This transformation may affect the spectral reflectance of Jupiter Trojans in a different way compared to KBOs, thereby providing a useful framework for possibly differentiating and determining the formation and history of small bodies. Along with allotropes, we report the production of organo-sulfur molecules. Sulfur molecules produced in our experiment have been recently detected by Rosetta in the coma of 67P/Churyumov–Gerasimenko. The very weak absorption of sulfur polymers in the infrared range hampers their identification on Trojans and KBOs, but these allotropes strongly absorb light at UV and Visible wavelengths. This suggests that high signal-to-noise ratio UV–Vis spectra of these objects could provide new constraints on their presence.

• OSTI ID: 22679858
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 846; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
AMMONIA
ELECTRONS
HYDROGEN SULFIDES
ICE
IRRADIATION
JUPITER PLANET
METHANOL
MOLECULES
SIGNAL-TO-NOISE RATIO
SIMULATION
SOLAR SYSTEM
SPECTRAL REFLECTANCE
SULFUR
THERMAL DESORPTION SPECTROSCOPY
ULTRAVIOLET SPECTRA
VISIBLE RADIATION
VISIBLE SPECTRA
WATER