The James Webb Space Telescope has achieved yet another milestone with its first exoplanet discovery confirmation. Peering 41 light years into the cosmos, the telescope found a planet in the Octans constellation with a diameter 99 per cent that of Earth’s – meet LHS 475 b.
A team of astronomers from the Johns Hopkins University Applied Physics Laboratory, led by Kevin Stevenson and Jacob Lustig-Yaeger, first spotted evidence of the candidate exoplanet while sifting through data from NASA’s Transiting Exoplanet Survey Satellite (TESS). However, it was the telescope’s Near-Infrared Spectrograph (NIRSpec) that confirmed the planet’s existence by observing two transits in front of its parent star. “There is no question that the planet is there. Webb’s pristine data validate it,” Lustig-Yaeger declared in a NASA press release.
The James Webb Space Telescope is the only telescope in operation today that possesses the resolving capabilities to accurately characterize the atmospheres of Earth-sized exoplanets. The research team is still working to determine the planet’s atmosphere by analyzing its transmission spectrum. There is a chance that the planet may be devoid of its critical gaseous insulation, but it could also be hiding a very small atmosphere close to the surface.
“Counterintuitively, a 100% carbon dioxide atmosphere is so much more compact that it becomes very challenging to detect,” said Lustig-Yaeger. The team is confident that the planet does not possess an oppressive atmosphere similar to that of Saturn’s moon Titan. “There are some terrestrial-type atmospheres that we can rule out. It can’t have a thick methane-dominated atmosphere,” he said.
The surface of the planet appears to be around 300 Celsius, several hundred degrees warmer than Earth. If cloud cover is discovered in subsequent studies, it could suggest a greenhouse world climate closer to Venus. The researchers have also confirmed that LHS 475 b maintains a tidal-locked orbit with its star of just two days. Though too close to attempt with our own sun, because LHS circles a red dwarf that’s producing less than half of our sun’s energy, it can theoretically maintain an atmosphere.