An approximately 1300 light years from us removed from us has given astronomers initial insights into the early stages of a new planetary system – the time when the first dust granules from the stellar primal cloud. The recordings of the James-Webb telescope and the Alma radio and adolescent service show the spectral signature of still gaseous silicon oxide indoors of the protoplans. However, crystalline silicate grains can already be detected further outside, at a distance of around 2.2 astronomical units from the star. They represent the first components of the rock, from which planets later form. According to the team, this is the first evidence of such minerals in such a young planetary system. It provides valuable insights into it, as our solar system once started.
Planets are formed in the rotating disc made of gas and dust around young stars – our solar system also has its origin in such a protoplanetary disc. Initially, the material in this disc is so hot that interstellar dust evaporates and the material of the later planet blocks are still gaseous. When the gas starts to cool off in the outside area of this “primeval cloud”, the first minerals condense. “These first high-temperature minerals, which were condensed from the gas reservoir, start the clock for planet formation,” explain Melissa McClure from the University of Leiden in the Netherlands and her colleagues. From these initially tiny particles, larger granules and crumbs gradually grow up until the first kilometer -sized planetesimal – the chunks from which the planets form.
Freshly condensed minerals on the protostern
But this first stage of planet formation has never been observed directly. Astronomers have already found protoplanetars and the preliminary stages of new planets, but they were all at a much later stage. “We always knew that the first fixed components of planets have to form at an earlier point in time,” explains McClure. The condensation of the first planetary minerals takes place a few hundred thousand years after the start of star formation. But at this point in time, the protoster is still surrounded by a shell of gas and dust, from which it attracts material and thereby grows further. However, these flows of materials and the dense shell make it difficult to look into the inner area of the protoplanetarian disc to look such a young protoster.
(Video: European Southern Observatory (ESO)
Now the protoster Hops-315 has given them this insight for the first time. The Jungstern, which is around 1300 light years away, stands to us in such a cheap angle that astronomers can look inside through a gap of the dusty shell. The team around McClure took advantage of this opportunity to examine Hops-315 with the high-resolution spectrographs of the James-Web-WEB-WELTRAUMTELESKOP and the radioa-lescopes of the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile. “The high spectral resolution of these instruments reveals a rich spectrum, dominated by the strong absorption signatures of icy and rocky solids and plenty of molecules in the gas phase,” report the astronomers. In the spectra, they discovered the signature of gaseous silica oxide (SIO) and crystalline silicates. The inclusions of meteorites and asteroids in the solar system are known that calcium and aluminum-rich silicate minerals are among the oldest and first that condense in the beginning of the planet formation. The detection of the silicate crystals around Hops-315 now confirms this.
Valuable insights also into solar early history
“This process has never been observed in a protoplanetary disc-or somewhere else outside of our solar system-” says co-author Edwin Bergin from the University of Michigan. Further analyzes of the observation data revealed the astronomers, where these first minerals crystallize on protosers. McClure and her colleagues demonstrated the spectral signatures of the silicate crystals in an area that is less than 2.2 astronomical units from protostern Hops-315. This means that these mineral particles are at a distance from the star, which roughly corresponds to that of the asteroid belt of our sun. “We can actually find the minerals in this extrasolar system at the same place where we have also found them in asteroids in the solar system,” says McClee’s colleague Logan Francis.
The new observations thus confirm models of this early stages of planet formation. At the same time, they help to better understand the history of our own planetary system. “This system is one of the best known to examine some of the processes that have also taken place in our solar system,” says co-author Merel van ‘t Hoff from Purdue University in the USA. “We see a system here that looks like our solar system at the beginning of its creation.”
Source: Melissa McClure (Leiden University, Netherlands) et al., Nature, DOI: 10.1038/S41586-025-09163-Z
