Since its launch in December 2021, the James Webb Space Telescope (JWST) has been breaking records.
Now the instrument has spotted its first planet around a star other than our own, and with an estimated diameter equal to about 99 percent that of Earth, it looks somewhat familiar.
Observations by NASA’s Transiting Exoplanet Survey Satellite (TESS) had hinted that the planet was there, but now high-resolution images provided by the Near-Infrared Spectrograph (NIRSpec) aboard JWST have confirmed it.
Despite the similarity in size, the planet is thought to be much hotter than our own world, orbiting a red dwarf star close enough to complete one orbit in just two days.
“There’s no doubt the planet is there,” says astronomer Jacob Lustig-Yager of the Johns Hopkins University Applied Physics Laboratory in Maryland. “Webb’s daily data confirmed it.”
This newly discovered object is located 41 light-years away in the constellation Octans and has been designated LHS 475 b. As with other exoplanets, it was spotted by looking at the shadow it creates as it passes in front of the star.
What makes JWST special is that it can look at transmission spectra; the range of wavelengths of light filtered around the planet that can reveal the qualities of its atmosphere.
The readings show that LHS 475 b does not have a methane-dominated atmosphere. (NASA/ESA/CSA/L. Hustak (STScI))
So far, we don’t have enough data to tell us what, if any, atmosphere LHS 475 b has. So far, astronomers are confident that it lacks a dense, methane-rich atmosphere like the one that surrounds Saturn’s moon Titan.
“The telescope is so sensitive and the data is so precise that we could easily detect several different molecules, but we still don’t see much,” said astrophysicist Ortiz Ceballos of the Harvard-Smithsonian Center for Astrophysics in Massachusetts.
But they cannot rule out a shallow atmosphere consisting of pure carbon dioxide.
The extra precision offered by JWST means researchers can search for stars and planets that are much smaller. Telescopes typically look for exoplanets larger than Jupiter, about 11 times the width of Earth.
Information is also being collected at a rapid pace: it only took two transits (or passes in front of the star) of JWST to identify LHS 475 b and some of its features. Further reading should tell us more about what we are dealing with here.
We’re also seeing JWST produce some absolutely stunning images of deep space, thanks to the sensitivity of its onboard instruments – and it’s only been in operation for just over a year. There is much more to come.
“These first observations of a rocky Earth-sized planet open the door to many future opportunities for studying rocky planet atmospheres with Webb,” said Mark Clampin, director of the Astrophysics Division at NASA Headquarters in Washington, DC.
“The web is bringing us closer and closer to a new understanding of Earth-like worlds outside our solar system, and the mission is just beginning.”
The findings were presented at a meeting of the American Astronomical Society on Wednesday, January 11, 2023.
Add Comment