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Effect of H₂S on the Near-infrared Spectrum of Irradiation Residue and Applications to the Kuiper Belt Object (486958) Arrokoth

Mahjoub, Ahmed and Brown, Michael E. and Poston, Michael J. and Hodyss, Robert and Ehlmann, Bethany L. and Blacksberg, Jordana and Choukroun, Mathieu and Eiler, John M. and Hand, Kevin P. (2021) Effect of H₂S on the Near-infrared Spectrum of Irradiation Residue and Applications to the Kuiper Belt Object (486958) Arrokoth. Astrophysical Journal Letters, 914 (2). Art. No. L31. ISSN 2041-8205. doi:10.3847/2041-8213/ac044b.

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On 2019 January 1, the New Horizons spacecraft flew by (486958) Arrokoth, a small body in the Kuiper Belt that is the most distant object ever visited by a spacecraft. A strong unidentified absorption band was observed in the spectrum of Arrokoth at 1.8 μm. We report here experimental evidence suggesting that the near-infrared spectrum of Arrokoth is indicative of sulfur-rich, tholin-like organic residue. The spectra of organic residues produced by irradiating ice mixtures "with H₂S" CH₃OH:NH₃:H₂S:H₂O (3:3:3:1) and "without H₂S" CH₃OH:NH₃:H₂O (3:3:1) were measured to study the effect of H₂S. The "with H₂S" sulfur-rich laboratory-synthesized organic residue displays an absorption band at 1.8 μm that is absent in the spectrum of "without H₂S" sample. This feature matches the Arrokoth spectrum better than any other expected material. This suggests the past presence of H₂S ice on the surface of Arrokoth and a role for Kuiper Belt objects as a key S reservoir in the early solar system.

Item Type:Article
Related URLs:
URLURL TypeDescription
Mahjoub, Ahmed0000-0003-1229-5208
Brown, Michael E.0000-0002-8255-0545
Poston, Michael J.0000-0001-5113-1017
Hodyss, Robert0000-0002-6523-3660
Ehlmann, Bethany L.0000-0002-2745-3240
Choukroun, Mathieu0000-0001-7447-9139
Hand, Kevin P.0000-0002-3225-9426
Alternate Title:Effect of H2S on the Near-infrared Spectrum of Irradiation Residue and Applications to the Kuiper Belt Object (486958) Arrokoth
Additional Information:© 2021. The American Astronomical Society. Received 2021 April 15; revised 2021 May 11; accepted 2021 May 21; published 2021 June 17. This work has been supported by the NASA/RDAP program and by the Keck Institute for Space Studies (KISS). This work has been conducted at the JPL, Caltech, under a contract with the National Aeronautics and Space Administration (NASA) and at the Caltech Division of Geological and Planetary Sciences.
Group:Keck Institute for Space Studies
Funding AgencyGrant Number
Keck Institute for Space Studies (KISS)UNSPECIFIED
Subject Keywords:Astrochemistry; Solar system; Small Solar System bodies; Laboratory astrophysics; Trans-Neptunian objects; Kuiper belt
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Astrochemistry (75); Solar system (1528); Small Solar System bodies (1469); Laboratory astrophysics (2004); Trans-Neptunian objects (1705); Kuiper belt (893)
Record Number:CaltechAUTHORS:20210629-165229618
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Official Citation:Ahmed Mahjoub et al 2021 ApJL 914 L31
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109646
Deposited By: Tony Diaz
Deposited On:29 Jun 2021 22:22
Last Modified:29 Jun 2021 22:22

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