NASA, ESA, CSA, Joseph Olmsted (STScI)
The James Webb Space Telescope has identified a rich mixture of gas swirling in the skies of a hot Jupiter-like world orbiting a star about 700 light-years from Earth.
In addition to carbon dioxide, water and other molecules, described in a series of new scientific papers published online, researchers say the telescope spotted signs of sulfur dioxide.
It must have been product by a chain of chemical reactions in the planet’s atmosphere, triggered by light from the Sun-like star that this gas giant planet orbits closely, circling around once every four days.
“It’s very exciting,” says Jacob beanastronomer at the University of Chicago.
He notes that light-triggered reactions are an important part of planetary atmospheres. In the Earth’s atmosphere, for example, sunlight produces ozone, which blocks harmful radiation from reaching the planet’s surface. But this kind of chemistry had never been unambiguously observed in the atmosphere of a planet outside our solar system before.
Understanding how it works on other worlds “is going to be crucial to understanding life on other planets,” Bean says.
Scientists have detected thousands of planets orbiting distant stars, almost always indirectly, by looking at the stars with telescopes to see how they are affected by the presence of orbiting planets. In most cases, researchers know nothing about the planets other than the approximate size of the worlds and the distance from the star.
Sometimes, however, they have been able to get clues about planetary atmospheres, by analyzing filtering starlight. This is because different molecules absorb different wavelengths of light.
The Hubble Space Telescope, for example, discovered a surprising amount of water vapor in the atmosphere of this particular planet, called WASP-39 b.
So when NASA’s new flagship telescope, the James Webb Space Telescope, was launched in December, scientists were eager to peer into this planet to compare the view provided by their new instruments to what had already been seen with Hubble.
“The Hubble observations have been confirmed, but we’ve gotten so much deeper into the understanding of this planet by revealing all these different molecules and being able to characterize their abundances much more precisely, and then seeing things that we didn’t expect. really.” Bean said.
“Like sulfur dioxide, that’s not something we’ve ever had a chance to see with Hubble,” Bean says. “But it was pretty easy and kind of came out of those early James Webb observations.”
As well as detecting a host of different molecules in the atmosphere, astronomers have also seen signs that this planet has patchy and scattered cloud cover, he adds.
“It’s not completely darkened,” says Bean. “It’s always wonderful when you can learn something new about one of these types of planets that allows me to create, at least in my head, a better mental image of what the planet looks like.”