The camera of the nearby JWST infrared has captured the structure of NGC 346, a metal -poor stars cluster in the small Magellanic cloud that imitates those in the early universe. The discs that form the planet in the cluster can survive for 30 million years, longer than scientists thought possible. Credit: NASA, ESA, CSA, STSCI, A. Pagan (STSCI)
How did we get here? Few topics in astronomy intrigue us more than this simple question of five words. Yet simplicity hides multiple layers of complexity. How was the universe born? How did the stars formed from an initial mix of most hydrogen gases and helium? How did the planets grow up in dusty discs surrounding these stars? And even the answers to these questions cannot explain how life and intelligence have appeared.
When the James Webb Space Telescope (JWST) started its mission, the scientists hoped that it would shed light on the key phase of the planet’s formation. Mission accomplished. A team of scientists found convincing evidence that the planets in the first days of the cosmos developed for surprisingly long periods.
Before JWST, astronomers studied mainly regions that form milk stars with compositions similar to the sun. These observations have shown that the records that form the planet do not last much longer than 2 million years. It is not much time for the granules of dust united, it combines with small rocks and creates huge nuclei that could become in planet -size bodies.
And these results could not explain most of the stars of the universe, which formed billions of years ago. The dust was scarce because few heavier elements than the helium, what astronomers call metals, then existed. The theorists thought that the lack of dust would allow the emission of X -rays of a star to wipe out any disc within one million years of years.
A shock of hubbles
But the Hubble Space Telescope raised serious questions about this scenario. In 2003, he discovered a planet 2.5 times the mass of Jupiter that surrounds a binary white star nana of neutron in the globular cluster of the Milky Way M4. These clusters have few metals and, in some way, one of them managed to create a huge planet.
Later that decade, Hubble studied the young Cluster Star NGC 346 in the small cloud of Magellanic (SMC), a galaxy of companions for the Milky Way located about 200,000 light years away. Although nearby, the SMC boasts a metallicity only about an eighth that of the sun, imitating what scientists find in very previous cosmic times. Hubble found about 200 stars of Cluster up to 30 million years that seemed to have records that form the planet.
JWST shows the point
“The results of Hubbles were controversial, going against not only empirical evidence in our galaxy but also against current models,” said the leader of the team Guido de Marchi of the European Center for Research and Space Technology in Noordwijk, the Netherlands, in a press release. Yet JWST confirmed Hubble’s results. The scientists used the infrared spectrograde near JWST to study 10 stars similar to the sun between 20 and 30 million years in NGC 346. The spectri-the first of any stars similar to the sun in an external-year galaxy revealed molecular hydrogen, confirming the existence of surrounding discs.
“With Webb, we have a really strong confirmation of what we have seen with Hubble,” said De Marchi. “We must rethink the way we model the formation of the planet and the early evolution in the young universe.” The team reported its results in the problem of 20 December 2024 The astrophysical diary.
Astronomes can now breathe more easily knowing that the planets have more time to develop around low metallic stars than the nearby regions of the Galaxy of the Milky Way. A possibility that researchers suggest is that the stars in the poor regions of metal begin life in larger clouds of gas that produce larger records.
