Detection of carbon dioxide and hydrogen peroxide on the stratified surface of Charon with JWST

Silvia Protopapa; Ujjwal Raut; Ian Wong; John Stansberry; Geronimo L Villanueva; Jason Cook; Bryan Holler; William M Grundy; Rosario Brunetto; Richard J Cartwright; Bereket Mamo; Joshua P Emery; Alex H Parker; Aurelie Guilbert-Lepoutre; Noemi Pinilla-Alonso; Stefanie N Milam; Heidi B Hammel

doi:10.1038/s41467-024-51826-4

Detection of carbon dioxide and hydrogen peroxide on the stratified surface of Charon with JWST

Nat Commun. 2024 Oct 1;15(1):8247. doi: 10.1038/s41467-024-51826-4.

Authors

Silvia Protopapa¹, Ujjwal Raut^{2

3}, Ian Wong^{4

5

6}, John Stansberry^{6

7

8}, Geronimo L Villanueva⁴, Jason Cook⁹, Bryan Holler⁶, William M Grundy^{7

8}, Rosario Brunetto¹⁰, Richard J Cartwright¹¹, Bereket Mamo^{2

3}, Joshua P Emery⁸, Alex H Parker¹², Aurelie Guilbert-Lepoutre¹³, Noemi Pinilla-Alonso¹⁴, Stefanie N Milam⁴, Heidi B Hammel¹⁵

Affiliations

¹ Southwest Research Institute, Boulder, CO, USA. silvia.protopapa@swri.org.
² Southwest Research Institute, San Antonio, TX, USA.
³ University of Texas at San Antonio, San Antonio, TX, USA.
⁴ NASA Goddard Space Flight Center, Greenbelt, MD, USA.
⁵ American University, Washington, DC, USA.
⁶ Space Telescope Science Institute, Baltimore, MD, USA.
⁷ Lowell Observatory, Flagstaff, AZ, USA.
⁸ Northern Arizona University, Flagstaff, AZ, USA.
⁹ Pinhead Institute, Telluride, CO, USA.
¹⁰ Université Paris-Saclay, CNRS, Institut d'Astrophysique Spatiale, Orsay, France.
¹¹ Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
¹² SETI Institute, Mountain View, CA, USA.
¹³ LGL-TPE, UMR 5276 CNRS, Université Lyon 1, ENS, Villeurbanne, France.
¹⁴ Florida Space Institute, University of Central Florida, Orlando, FL, USA.
¹⁵ Association of Universities for Research in Astronomy, Washington, DC, USA.

Abstract

Charon, Pluto's largest moon, has been extensively studied, with research focusing on its primitive composition and changes due to radiation and photolysis. However, spectral data have so far been limited to wavelengths below 2.5 μm, leaving key aspects unresolved. Here we present the detection of carbon dioxide (CO₂) and hydrogen peroxide (H₂O₂) on the surface of Charon's northern hemisphere, using JWST data. These detections add to the known chemical inventory that includes crystalline water ice, ammonia-bearing species, and tholin-like darkening constituents previously revealed by ground- and space-based observations. The H₂O₂ presence indicates active radiolytic/photolytic processing of the water ice-rich surface by solar ultraviolet and interplanetary medium Lyman-α photons, solar wind, and galactic cosmic rays. Through spectral modeling of the surface, we show that the CO₂ is present in pure crystalline form and, possibly, in intimately mixed states on the surface. Endogenically sourced subsurface CO₂ exposed on the surface is likely the primary source of this component, with possible contributions from irradiation of hydrocarbons mixed with water ice, interfacial radiolysis between carbon deposits and water ice, and the implantation of energetic carbon ions from the solar wind and solar energetic particles.

Abstract

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