Planets like our Earth, including water planets, can form even in the harshest known star-forming environments, exposed to harsh ultraviolet light from massive stars. This is the main conclusion of the analysis of new observations of such an environment using the James Webb Space Telescope (JWST). These observations are the first of their kind; Such detailed observation was not possible before JWST. This is good news for Earth-like planets and life in the universe: There is a wide variety of environments in which such planets can form. The results are published in the journal Astrophysics Journal Letters.

Water and carbon molecules were detected in the disk of gas and dust surrounding a young solar-type star in one of the most extreme environments of our galaxy. Such disks are where planets form around newborn stars. A team of astronomers led by Maria C. Ramírez-Tannus of the Max Planck Institute for Astronomy (MPIA) used the James Webb Space Telescope to look at the inner region of the disk where Earth-like planets are expected. to form: so-called terrestrial planets, with a thin atmosphere covering the rock planet.

The disk, which astronomers have named XUE-1, is exposed to intense ultraviolet radiation from nearby hot, massive stars. But even in this harsh environment, observations revealed both water and simple organic molecules. “This result was unexpected and exciting,” says Ramírez-Tannus. “This shows that even in the harshest conditions of our Galaxy, there are suitable conditions for the formation of Earth-like planets and the formation of the necessary components for life.”

Unprecedented details of major star-forming regions

The new observations are the first of their kind. Previous detailed observations of planet-forming disks were limited to nearby star-forming regions that do not contain massive stars. Massive star-forming regions are quite different; Large numbers of stars form almost simultaneously, including some rare but extremely powerful very massive stars. About 10 billion years ago, during the “golden age” of star formation in the universe, most stars formed in such large clusters. Overall, more than half of all stars in our universe, including our own Sun, were born along with their planets in massive star-forming regions. However, nothing was known about the effect of such a harsh environment on the inner regions of the disks, where the formation of terrestrial planets was expected.

Massive stars are naturally very bright and emit large amounts of high-energy ultraviolet radiation. Their presence causes significant disturbances in those nearby. It remains an open question whether this failure would regularly prevent the formation of Earth-like planets around Sun-like stars, such that Earth-like planets would be located in such large clusters that are very rare, if not impossible, to form. There were convincing arguments that this might be the case. For example, ultraviolet radiation from massive stars disperses gas in the outer parts of the disk, preventing dust particles, which are the building blocks of Earth-like planets (as well as the cores of giant planets like Jupiter), from growing and drifting inward. . or Saturn). This could increase the likelihood of Earth-like planets forming.

Observations so far have not helped answer this question. Massive star-forming regions are rare in the modern Universe, and even the closest ones are very distant. Until recently, it was not possible to observe the small disks around sun-like stars in detail. Various planet-forming disks there was It is close enough to be observed in detail, is located in a quiet environment, is free of intense ultraviolet radiation from massive stars, and is therefore of no use in answering the question.

Investigating internal disks with JWST

This changed with the advent of JWST. Once the telescope became available for scientific observations, Ramírez-Tannus and XUE (Extreme Ultraviolet Environment) collaborated to successfully observe NGC 6357. Located 5,500 light-years away from Earth, this star is one of the closest massive stars. regions It is also the most promising observational target for answering the question about the inner disk: NGC 6357 contains more than ten bright high-mass stars; This ensures that some of the planet-forming disks visible in this region have been exposed to intense UV radiation for long periods of time. most of its existence. Diversity is an important factor: The region contains a variety of discs, some more exposed, others less.

“If intense radiation inhibits planet formation in the inner regions of protoplanetary disks, NGC 6357 is where we should see the effect,” says Arjan Beek of Stockholm University, co-principal investigator of the XUE collaboration. and second author of the article.

Observations made by astronomers recorded spectra: iridescent light distributions that allow us to assess the presence of specific molecules in the observed area. Ramírez-Tannus and colleagues surprisingly discovered that at least one of NGC 6357’s inner disks, XUE-1, is essentially indistinguishable from its counterparts when it comes to the presence (and properties) of key molecules. in low mass star forming regions.

Silicates, water and other molecules in harsh conditions

“We found large amounts of water, carbon monoxide, carbon dioxide, hydrogen cyanide and acetylene in the deepest parts of XUE-1,” says Ramírez-Tannus. “This provides valuable clues about the possible composition of the early atmospheres of the terrestrial planets that formed.” The researchers also found amounts of silicate dust similar to those found in low-mass star-forming regions. This is the first time such molecules have been discovered under such extreme conditions.

The observation is good news for Earth-like planets and life in the universe: It appears that the inner regions of protoplanetary disks around Sun-like stars located in some of the harshest star-forming environments are also capable of forming terrestrial stars. rocky planets, like their low-mass counterparts. They even provide copious amounts of water, an essential ingredient for life as we know it. By looking at a single disk, researchers cannot tell whether this means that many Earth-like planets were born in such environments. The XUE collaboration continues its observations with JWST examining 14 additional disks in different parts of NGC 6357; This will help solve an important problem.