
A team of astronomers has identified a potential new mechanism for bringing water to Earth, offering a promising departure from previous theories. Based on numerous observations of the Solar System, as well as observations of extrasolar debris disks by the ALMA radio telescope, the results are published in the journal Astronomy and Astrophysics.
Astrophysicists propose an innovative explanation for the origin of water on planets, without resorting to violent impacts by asteroids or comets. A study published in Astronomy & Astrophysics, led by Paris Observatory, shows that water could form directly in the protoplanetary disks surrounding young stars, thanks to natural chemical processes. This discovery overturns traditional models and offers new perspectives for understanding the diversity of planetary environments and the emergence of habitability.
The dominant model for the origin of water
Until recently, scientists believed that terrestrial water originated from impacts of water-rich celestial bodies, such as comets or asteroids, which would have delivered water after the initial formation of planets. However, this model is limited: it does not explain certain isotopic clues or the presence of water on worlds formed in less dynamic environments.
A chemical and universal approach
In this research, astronomers examined chemical processes in protoplanetary disks. They have shown that water can form directly from the interaction between hydrogen and oxygen present in these disks, long before planets are fully formed. This mechanism could explain the ubiquitous presence of water in stellar systems, irrespective of the intensity of impacts.
Prospects for the study of exoplanets
This discovery widens the field of potentially habitable planets. Planets located in quiet systems, where impacts are rare, could nonetheless contain large quantities of water. In the future, these results will guide research into protoplanetary disks and refine the search for exoplanets suitable for life.
Study available in Astronomy & Astrophysics.
An impact-free mechanism to deliver water to terrestrial planets and exoplanets. Quentin Kral et al, Astronomy & Astrophysics , December 3, 2024.
DOI : 10.1051/0004-6361/202451263