The discovery of S2 in comet IRAS-Araki-Alcock 1983d

A’Hearn, M. F.; Schleicher, D. G.; Feldman, P. D.

doi:10.1086/184158

Cited by 136 publications

(39 citation statements)

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“…Disulfur, S 2 , is ubiquitous in comets. This molecule was first detected in the UV spectra of comet C/1983 H1 (Ahearn et al 1983). Since then, S 2 has been identified in many comets (Swamy & Wallis 1987;Laffont et al 1998;Kim et al 2003).…”

Section: Sulfur Irradiation Products In Cometary Materialsmentioning

confidence: 95%

“…Recently the ROSINA mass spectrometer on board the Rosetta spacecraft detected S 2 at a distance of 3.15 au from the Sun, with an abundance of ∼10 −5 compared to water (Le Roy et al 2015). Ahearn et al (1983) suggested that S 2 comes from (or is formed very close to) the comet nucleus rather than by gas phase chemistry in the cometary coma. Indeed, S 2 is observed at distances larger than 3 au, where the gas density is very low and collisions are rare, these conditions are not convenient for gas phase recombination reactions.…”

Section: Sulfur Irradiation Products In Cometary Materialsmentioning

confidence: 99%

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Production of Sulfur Allotropes in Electron Irradiated Jupiter Trojans Ice Analogs

Mahjoub

Poston

Blacksberg

et al. 2017

ApJ

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In this paper, we investigate sulfur chemistry in laboratory analogs of Jupiter Trojans and Kuiper Belt Objects (KBOs). Electron irradiation experiments of CH 3 OH-NH 3 -H 2 O and H 2 S-CH 3 OH-NH 3 -H 2 O ices were conducted to better understand the chemical differences between primordial planetesimals inside and outside the sublimation line of H 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 3 and S 4 ) after the irradiation of H 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 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 organosulfur 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.

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Section: Sulfur Irradiation Products In Cometary Materialsmentioning

confidence: 95%

Section: Sulfur Irradiation Products In Cometary Materialsmentioning

confidence: 99%

Production of Sulfur Allotropes in Electron Irradiated Jupiter Trojans Ice Analogs

Mahjoub

Poston

Blacksberg

et al. 2017

ApJ

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“…For a total S 2 column density of 10 16 molecules cm −2 , Yelle et al find that the photolysis rates at 1 AU in free space are ∼2.4 × 10 −3 s −1 , ∼4.0 × 10 −3 s −1 , and ∼5.8 × 10 −3 s −1 for S 2 molecules at 100 K, 300 K, and 1000 K, respectively, and the J values also change with the assumed total column density of S 2 . We use this information combined with the actual low-temperature cross sections, a dissociation threshold of 278 nm, and an assumed photodissociation efficiency of ∼77% to determine roughly appropriate photolysis cross sections for our model (see also A'Hearn et al 1983, de Almeida and Singh 1986, and Kim et al 1990 for further information about the photolysis lifetime of S 2 ). For S 3 , we use the measured photoabsorption cross sections of Billmers and Smith (1991), and we assume that photolysis into the branch S 3 → S 2 + S occurs with 100% efficiency at wavelengths below the threshold 455 nm.…”

Section: A3 Photochemical Reactionsmentioning

confidence: 99%

Photochemistry of a Volcanically Driven Atmosphere on Io: Sulfur and Oxygen Species from a Pele-Type Eruption

Moses

Zolotov

Fegley

2002

Icarus

100

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“…Assuming that all of the CS observed in the coma comes from ca2, then CS2/H20,-&.001, i.e., CS 2 is a trace constituent of the nucleus. UV observations of the "Earth-grazing" comet IRAS-Araki-Alcock (1983d) dramatically revealed the presence of S2, a molecule which had never been observed previously in any astrophysical environment [24]. Since the S2 discovery coincided with an "outburst" in cometary activity, and since the signal virtually disappeared during late_ observations, the presence of S2 in IRAS-Araki-Alcock may not be typical.…”

Section: _ Major Sulfur-bearing Specie S: Cs2 $2mentioning

confidence: 91%

The Volatile Composition of Comets

Weaver

1989

Highlights of Astronomy

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Comets may be our best probes of the physical and chemical conditions in the outer regions of the solar nebula during that crucial period when the planets formed. The volatile composition of cometary nuclei, in particular, can be used to decide whether comets are the product of a condensation sequence similar to that invoked to explain the compositions of the planets and asteroids, or if comets are simply agglomerations of interstellar grains which ' have been insignificantly modified by the events that shaped the other bodies in the solar system. Although cometary nuclei are not generally accessible to observation, observations of comet_) comae can illuminate at least some of the mysteries of the nuclei provided one has a detailed knowledge of the excitation conditions in the coma and also has access to basic atomic and molecular data on the many species present in comets. This paper examines the status of our knowledge of the volatile composition of cometary nuclei and discusses how these data are obtained.

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The discovery of S2 in comet IRAS-Araki-Alcock 1983d

Cited by 136 publications

References 0 publications

Production of Sulfur Allotropes in Electron Irradiated Jupiter Trojans Ice Analogs

Production of Sulfur Allotropes in Electron Irradiated Jupiter Trojans Ice Analogs

Photochemistry of a Volcanically Driven Atmosphere on Io: Sulfur and Oxygen Species from a Pele-Type Eruption

The Volatile Composition of Comets

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