🔭 Never-before-detected ice in the solar system

2024-07-15 06:00:15

Trans-Neptunian Objects (TNOs) are small, primitive bodies in our outer Solar System, orbiting beyond Neptune. Formed quite far from the Sun, these objects still contain a wealth of information about their formation over 4 billion years ago, at theinverse dwarf planets like Pluto that may have evolved internal majeure.

OTNs have also witnessed planetary migration processes that have, for the majority, redistributed them far from their region of formation. Until now, observations of OTNs have been limited, providing a very partial characterization of their chemical composition: only water and methanol ices were detected on a handful of objects.

A major observation program by the James Webb Space Telescope recently provided the first view ofensemble of OTNs. Observations of 59 objects obtained with the NIRSpec instrument were analyzed by a team of research international involving scientists from CNRS Terre & Universe. Infrared spectra reveal first-ever detections of CO2 and CO ices on small bodies of the Solar system external.

Against all expectations, CO2 is very widespread, present on 95% of objects in variable proportions. While CO is not stable in the trans-Neptunian region, it is nevertheless detected together with CO2 on 47% of objects. This diversity of composition, reflected by variations in abundance but also in the physicochemical state of the ice, will make it possible to trace the history of OTNs to find their place of formation in the protoplanetary disk.

If CO2 could have been inherited from disk protoplanetary, CO would more likely be formed by interaction of the surface with the solar wind and cosmic rays. Remarkably, 13CO2 is also detected which opens the possibility of studying the isotopic ratio of carbone across the outer solar system.

Infrared signature of the fundamental bands of CO2 and CO on OTN surfaces (left) and distribution of their detection within the different dynamic groups of OTNs (right).
© De Prá et al. Nature Astronomy, 05/24.

Reference:
De Prá, MN, Hénault, E., Pinilla-Alonso, N. et al.
Widespread CO2 and CO ices in the trans-Neptunian population revealed by JWST/DiSCo-TNOs.
Nat Astron (2024).

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#Neverbeforedetected #ice #solar #system