Issue |
A&A
Volume 694, February 2025
|
|
---|---|---|
Article Number | A126 | |
Number of page(s) | 16 | |
Section | Planets, planetary systems, and small bodies | |
DOI | https://doi.org/10.1051/0004-6361/202452321 | |
Published online | 07 February 2025 |
Irradiation origin and stability of CO on trans-Neptunian objects
Laboratory constraints and observational evidence from JWST/DiSCo-TNOs
1
Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale,
Orsay,
France
2
Institute for Space Sciences and Technologies in Asturias, Universidad de Oviedo,
Spain
3
University of Central Florida, Department of Physics,
Orlando,
FL,
USA
4
Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, UMR 5276 CNRS, UCBL, ENSL,
Villeurbanne,
France
5
Max-Planck-Institut für extraterrestrische Physik,
Garching,
Germany
6
Florida Space Institute, University of Central Florida,
Orlando,
FL,
USA
7
Space Telescope Science Institute,
Baltimore,
MD,
USA
8
Northern Arizona University,
Flagstaff,
AZ,
USA
9
Instituto Astrofísico de Canarias,
La Laguna,
Tenerife,
Spain
10
Universidad de La Laguna,
Tenerife,
Spain
11
Fundación Galileo Galilei-INAF,
La Palma, S.C. de Tenerife,
Spain
12
Instituto de Astrofísica e Ciências do Espaço, Departamento de Física, Universidade de Coimbra,
Portugal
13
University of Canterbury, School of Physical and Chemical Sciences – Te Kura Matū,
Christchurch,
New Zealand
14
Lowell Observatory,
Flagstaff,
AZ,
USA
★ Corresponding author; elsa.henault@universite-paris-saclay.fr
Received:
20
September
2024
Accepted:
5
December
2024
Context. The James Webb Space Telescope large program DiSCo-TNOs has recently shown that CO2 ice is ubiquitous on 54 mediumsize trans-Neptunian objects (TNOs). TNO surfaces are found to define three main spectral and thus compositional groups that are likely linked to their position before planetary migration. CO ice is observed on the spectral type that is richest in CO2 and on the type that is richer in CH3OH and organics. Considerations on the thermal evolution of TNOs predicted the depletion of hypervolatiles such as CO from their surface layers, however.
Aims. We investigate a potential irradiation origin of CO as well as its stability by studying the distribution of CO in two TNO compositional types and compared it with irradiation experiments.
Methods. We studied the 4.68 µm band of CO and the 2.70 µm band of CO2 to probe the relation between the two molecules in 33 TNOs. We performed ion irradiation experiments on CO2 and CH3OH ices at 45 and 60 K with 30 keV H+ . We compared the laboratory spectra to TNO observations by focusing on the band areas and positions.
Results. We find that the two types of surfaces in which CO is detected are very distinct in terms of their relative abundances and chemical environment. CO that is observed on surfaces that are rich in CO2 are consistent with being produced by CO2 irradiation, specifically, at 45 K. On objects that are rich in CH3OH and complex organics, CO is more likely formed by irradiation of CH3OH. As the CO band areas are only partly related with temperature, the chemical environment plays a major role in the CO retention.
Conclusions. We find that the CO that is observed on TNO surfaces is compatible with being a secondary molecule that is entirely formed by late irradiation processes. Its abundance and stability is mostly controlled by the matrix from which it formed.
Key words: astrochemistry / solid state: volatile / methods: observational / techniques: spectroscopic / Kuiper belt: general
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.