Webb confirms his first planet: an Earth-sized world 41 light-years away

12 Jan. () –

Observations from the NASA/ESA/CSA James Webb Space Telescope have served for the first time to confirm the presence of a planet outside the solar system.

Formally classified as LHS 475 b, the planet is almost exactly the same size as our own, with 99% of the diameter of the Earth. It is relatively close, only 41 light-years away, in the constellation Octans.

The discovery team is led by Kevin Stevenson and Jacob Lustig-Yaeger, both of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The team decided to look at this target with Webb after carefully reviewing data from NASA’s Transiting Exoplanet Survey Satellite (TESS), which pointed to the planet’s existence.

Webb’s Near Infrared Spectrograph (NIRSpec) captured the planet easily and clearly with just two transit observations. “There is no doubt that the planet is there. Webb’s pristine data validates it,” stated Lustig-Yaeger. “The fact that it’s also a small, rocky planet is impressive for the observatory,” Stevenson added. it’s a statement.

“These first observational results from a rocky, Earth-sized planet open the door to many future possibilities for studying the atmospheres of rocky planets with Webb,” agreed Mark Clampin, director of the Division of Astrophysics at NASA Headquarters. in washington. “Webb is bringing us ever closer to a new understanding of Earth-like worlds outside the solar system, and the mission has only just begun.

Among all the telescopes in operation, only Webb is capable of characterizing the atmospheres of Earth-sized exoplanets. The team tried to assess what is in the planet’s atmosphere by analyzing its transmission spectrum. Although the data shows that it is a terrestrial planet the size of Earth, They still don’t know if it has an atmosphere.

“The data from the observatory is precious”, said Erin May, also of the Johns Hopkins University Applied Physics Laboratory. “The telescope is so sensitive that it can easily detect a number of molecules, but we cannot yet draw any definitive conclusions about the planet’s atmosphere.”

Although the team cannot conclude what is present, they can say for sure what is not. “There are some terrestrial-type atmospheres that we can rule out,” Lustig-Yaeger explained. “It cannot have a thick methane-dominated atmosphere, similar to that of Saturn’s moon Titan.”

The team also notes that while the planet may not have an atmosphere, there are some atmospheric compositions that have not been ruled out, such as an atmosphere of pure carbon dioxide. “Counterintuitively, a 100% carbon dioxide atmosphere is so much more compact that it’s very difficult to detect,” said Lustig-Yaeger. The team needs even more precise measurements to distinguish an atmosphere of pure carbon dioxide from no atmosphere at all. The researchers are scheduled to obtain additional spectra with new observations this summer.

Webb also revealed that the planet is a few hundred degrees warmer than Earth, so if clouds are detected it could lead researchers to conclude that the planet is more like Venus, that it has a carbon dioxide atmosphere and is perpetually shrouded in dense clouds. “We are at the forefront of the study of small, rocky exoplanets,” says Lustig-Yaeger. “We’ve only just begun to scratch the surface of what their atmospheres might look like.”

The researchers also confirmed that the planet completes one orbit in just two days, information that was revealed almost instantly by Webb’s precise light curve. Although LHS 475 b is closer to its star than any other planet in the solar system, its red dwarf star is less than half the temperature of the Sun, so researchers project it could still harbor an atmosphere.

The team’s results were presented at a press conference at the American Astronomical Society (AAS).