Atmospheric composition of the gas-rich exoplanet WASP-39b as observed with a 10-billion telescope

The carbon to oxygen ratio on the planet was low. This suggests that WASP-39b had absorbed a high amount of water as ice, probably when it was in a different position, and that it formed much farther out in its solar system, perhaps comparable to “where Jupiter is” around our Sun, says Eva-Maria Ahrer, an astronomer at the University of Warwick, UK, and lead author on one of the papers3.

What researchers have seen so far is preliminary and doesn’t yet indicate what sorts of atmospheres these planets might actually have. But if they have dense atmospheres with intriguing molecules such as carbon dioxide or methane, the US$10-billion telescope will be able to detect them in the coming months and years. No other observatory has been powerful enough to spot these atmospheres.

The telescope, launched in December 2021, observed the planet for more than 40 hours in July. Initial results showed carbon dioxide in the planet’s atmosphere. It was the first time that the gas had been seen on an exoplanet.

The astronomer who led the observation team says that photochemistry is an important process on other potentially habitable planets. Until now, “we’ve only been able to test our understanding of photochemistry in our Solar System. But planets around other stars give us access to completely different physical conditions.”

Such inward migration of hot Jupiters is expected, to explain their proximity to their stars. What remains unclear is whether this is a slow process, over perhaps tens of millions of years, or whether it results from a gravitational ‘shove’ from another planet or star. Knowing WASP-39b’s composition could help astronomers to determine which scenario occurred.

The planet is tidally locked to its star, with the same face always pointing towards it, because of the immense gravitational attraction between them. Explanation of incomplete cloud cover is something that has never before been observed on an exoplanet. At the boundary of night and day, the planet is “only about 60% covered by clouds”, says Bean — perhaps because clouds evaporate as they reach the hotter (day) side and condense as they reach the cooler side.

TRAPPIST-1g: A super-Earth system with a Hydrogen-rich atmosphere and a faint planetary system mapped out by JWST

The astronomer at the University ofMontreal said during the symposium on the first results from JWST in Baltimore, Maryland, that they are in business.

The TRAPPIST-1 planetary system, mapped out in 2017, offers astronomers multiple chances at understanding the formation and evolution of Earth-sized worlds around a single star. The seven planets are very close to the star, and it’s relatively faint and cool.

Benneke showed the first JWST studies of TRAPPIST-1g. Since it is so large and has a Hydrogen-rich atmosphere, it would be easy to spot if it did not have a hydrogen-rich atmosphere. That could mean that the planet has a denser atmosphere, made of heavier molecules, such as carbon dioxide, or no atmosphere at all.

The first look to know what we were dealing with was necessary according to Knicole Coln, who was not involved in the work. Benneke declined to speak with reporters about the TRAPPIST-1g results, citing a paper under review at a scientific journal.