The The James Webb Space Telescope has confirmed the existence of its first exoplanet, which is rocky, 41 light-years from Earth, and almost the same size as Earth.
The existence of the exoplanet, classified as LHS 475bwas suggested by data from NASA’s TESS satellite, so the researchers decided to observe the object with James Webb, whose near-infrared spectrograph clearly captured that it was a planet outside the solar system.
The research team was led by Kevin Stevenson and Jacob Lustig-Yaegerfrom the Johns Hopkins University Applied Physics Laboratory (USA) and the results were presented at the meeting of the American Astronomical Society.
LHS 475b has 99% of the diameter of the Earth and it is relatively close, only 41 light-years away, in the constellation Octans.
“There is no doubt that the planet is there. The pristine data Webb validate it,” said Lustig-Yaeger, quoted in a statement from the European Space Agency (THAT).
“These first observational results for a rocky, Earth-sized planet open the door to many future possibilities to study” their atmospheres with Webb, noted Mark Clampin, director of the Division of Astrophysics at POT.
Illustration of the exoplanet LHS 475 b. (Image: NASA/ESA)
DOES IT HAVE AN ATMOSPHERE?
Of all the telescopes in operation, only Webb is capable of characterizing the atmospheres of Earth-sized exoplanets, so the team tried to assess that of the new exoplanet by analyzing its transmission spectrum.
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,” Lustig-Yaeger explained.
Although the team cannot conclude what is present, it can tell what is not and rule out the existence of some thick methane-dominated atmospheres, similar to that of Saturn’s moon Titan.
Although the planet may not have an atmosphere, there are some atmospheric compositions that have not been ruled out, such as one of pure carbon dioxide.
“Counter-intuitively, an atmosphere with 100% carbon dioxide is much more compact and difficult to detect“Lustig-Yaeger said.
So 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 it is a few hundred degrees warmer than Earth, so if clouds are detected it could lead researchers to conclude that it is more like Venus.which has a carbon dioxide atmosphere and is perpetually shrouded in dense clouds.
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 Sunso the researchers project that it could still harbor an atmosphere.
The researchers’ findings have opened up the possibility of locating Earth-size planets orbiting smaller red dwarf stars and also underscore “the precision of James Webb’s instruments,” Stevenson said.
For Lustig-Yager, thanks to James Webb, “Rocky exoplanets are the new frontier”.