The Webb telescope solves a 20-year-old planetary mystery raised by Hubble

How the planets evolve into the diversity of worlds we see in our universe remains one of the most pressing questions for scientists who unravel how we got here and where we are going.

Now, a group of scientists have used data from the Webb Space Telescope to solve a mystery raised by a veteran space telescope more than 20 years ago, which has shaken up what planetary scientists knew about how the first worlds took shape from the cosmic ether.

In 2003, the Hubble Space Telescope detected what appeared to be the oldest known planeta massive world that spans about 13 billion years. The discovery raised questions about how such worlds were born when their host stars were similarly young, and contained only small amounts of heavier elements – a crucial ingredient in the formation of planets as we know them.

In the new research, a team used the Webb telescope – a state-of-the-art space observatory capable of observing some of the oldest detectable light – to study stars in a nearby galaxy that also lack heavy elements. Those stars, the team found, have disks that form planets, and those disks are older than those surrounding the young stars in our galaxy.

“With Webb, we have a really strong confirmation of what we saw with Hubble, and we have to rethink how we model the formation of the planet and the early evolution in the young universe,” said Guido De Marchi, researcher at the European Center of Space Research and Technology. and lead author of the study, in a NASA liberation.

In the new study, published in The Astrophysical Journal earlier this month, the team observed stars in NGC 346, a star-shaped cluster in the Small Magellanic Cloud. The stars range in mass from about 0.9 times the mass of our Sun to 1.8 times the mass of our host star.

The team found that even the oldest stars they looked at are still accreting gas, and that the stars appear to have disks around them. This confirmed Hubble observations from the mid-2000s, which revealed tens of millions of years old stars that retained planet-forming disks – which are generally thought to dissipate after a few million years. years

In summary, the team wrote in the paper that the results “suggest that in a low-metallicity environment, circumstellar disks can live longer than previously thought.”

The researchers believe that the discs could remain for a couple of reasons. One possibility is that the lack of heavy elements actually benefits the discs, allowing them to better withstand the pressure of the star’s radiation, which would otherwise wear them out quickly. Another possibility is that sun-like stars form from large clouds of gas, which take longer to dissipate simply because they are larger.

“With more matter around the stars, the accretion lasts for a longer time,” said Elena Sabbi, the chief scientist for the National Science Foundation’s Gemini Observatory, part of the foundation’s NOIRLab, in the same version. “Discs take ten times longer to disappear. This has implications for how a planet forms, and the kind of system architecture you can have in these different environments. This is so exciting.”

The team used the Webb Space Telescope’s NIRSpec (Near-Infrared Spectrograph) instrument to inspect the stars bursting through the Small Magellanic Cloud. Last year, a team of scientists used NIRSpec to see silty clouds on a nearby exoplanet; earlier this year, the tool was used to detect the first so-called Einstein Zig-Zag in space. Unlike spectrographs in old space observatories, Webb NIRSpec can observe 100 targets simultaneously, speeding up the rate of data collection and, by proxy, discovery.

Looking at both old and young star-forming regions can help clarify the origins of our solar system, which is about 4.6 billion years old.