The low metallicity of stars did not hinder the formation of planets in the ancient universe.

In the early Universe, stars contained few heavy elements, which hindered the formation of planets. In conditions of low metallicity, protoplanetary disks dispersed before they could form bodies the size of Jupiter or larger. However, observations from the James Webb Space Telescope have revealed that even under such conditions, massive planets were forming in the dawn of the Universe.

2024-12-18 10:01:27https://naked-science.ru/article/astronomy/nizkaya-metallichnost-zve

In 2003, astronomers obtained compelling evidence for the existence of a massive planet orbiting a very old star—one nearly as old as the universe itself. The discovery seemed paradoxical, as the low metallicity of the ancient star (indicating a scarcity of heavy elements) should significantly shorten the lifespan of the protoplanetary disk. However, data from the Hubble Space Telescope showed the opposite, leaving scientists puzzled.

Now, to fully understand the situation, a research team led by Guido De Marchi from the European Space Agency (ESA) used the James Webb Space Telescope to study the NGC 346 cluster in the Small Magellanic Cloud—a nearby dwarf galaxy with heavy element content similar to that of the early universe.

The results of the scientific work, published in The Astrophysical Journal, revealed that gas and dust disks around sun-like stars in environments poor in heavy elements can persist for tens of millions of years—significantly longer than previously thought.

In particular, observations of the NGC 346 cluster helped identify several stars surrounded by planet-forming disks: spectral analysis of these objects showed clear signs of a gas accretion process and the presence of dust. The ages of the stars were found to be between 20 and 30 million years. In comparison, in areas enriched with heavy elements within our Galaxy, a typical disk around a star of solar mass dissipates within just two to five million years.

This discovery confirms the validity of the data obtained through Hubble and leads to a revision of existing models of planet formation and evolution in the early universe, as stars in low metallicity conditions disperse and blow away their disks at a slower rate.

“If disks ‘live’ ten times longer than we thought, then planets could form much more efficiently than those we observe today around stars with high metallicity,” said astronomer Elena Sabbi from the Gemini Observatory (USA) in an interview with Phys.org.

Astronomers also suggested that stars form from more massive gas clouds, creating a large and radiation-resistant disk. This scenario allows planets more time to grow and accumulate material, even in environments with few heavy elements.

The data obtained from the James Webb Space Telescope also imply that the formation of giant planets in the young universe may have been more common than previously believed.