An international team, led by Melissa McClure from Leiden Observatory, and involving the French researchers from the CNRS – Emmanuel Dartois from ISMO and Jennifer Noble from PIIM – have detected the signatures of gas and minerals in a protoplanetary disc, tracing the first stages of the evolutionary process of interstellar solids that could lead to the formation of a new planetary system.
Thanks to observations of the young protostar HOPS-315 (located in the Orion B molecular cloud, around 420 parsecs from Earth) carried out with the James Webb Space Telescope and the Atacama Large Millimetre Array, the team determined that these chemical signatures came from a small region of the disc around the star, equivalent to the orbit of the asteroid belt around the Sun.
It is theorised that terrestrial planets and small bodies like those in our Solar System formed from interstellar solids mixing with rocky solids that condense out from the hot gas around a young host star as that gas cools. However, the specific processes at play remain unclear.
The protostar HOPS-315 is positioned so as to allow a direct view of its inner gaseous disc, through a cavity in its outer envelope. The authors observed solids starting to condense from the cooling gas, a ‘start time’ for planet formation. Upon comparison of these observations with models, they suggest that the conditions resemble those necessary for the formation of planets similar to those in the Solar System.
This study is published in Nature:
https://www.nature.com/articles/s41586-025-09163-z
Link to the ESO press release:
https://www.eso.org/public/france/news/eso2512/
CONTACT
Melissa McClure :
Jenny Noble :
Emmanuel Dartois :
Here is HOPS-315, a young star where astronomers have observed signs of the earliest stages of planet formation. The image was captured using the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner. Combined with data from the James Webb Space Telescope (JWST), these observations reveal that hot minerals are beginning to solidify.
In orange, we see the distribution of carbon monoxide being expelled from the star in a butterfly-shaped outflow. In blue, we observe a narrow jet of silicon monoxide also streaming away from the star. Such gaseous winds and jets are common around newborn stars like HOPS-315.
The ALMA and JWST observations also indicate the presence of a disk of gaseous silicon monoxide surrounding the star, which is condensing into solid silicates — potentially marking the very first steps of planetary formation.
Credit:
ALMA (ESO/NAOJ/NRAO) / M. McClure et al.