In the first six months of its operation, the James Webb Space Telescope has already received visually stunning and scientifically impressive results, and recently recorded another major milestone: discovery of the first exoplanet. The planet, named LHS 475b, is located in the Aries constellation, 41 light-years from the Sun, and its diameter is 99% that of Earth.
A team of astronomers from Johns Hopkins University’s Applied Physics Laboratory, led by Kevin Stevenson and Jacob Lustig-Yaeger, first spotted signs of a candidate exoplanet while analyzing data from the TESS (Transiting Exoplanet Survey Satellite) space telescope. However, it was the James Webb Near Infrared Spectrograph (NIRSpec) that confirmed the existence of the planet by observing its two transits in front of the mother star.
“There is no question that the planet is there. Webb’s pristine data validate it,” Lustig-Yaeger said in NASA press-release.
A whole new world!
41 light-years away is the small, rocky planet LHS 475 b. At 99% of Earth’s diameter, it’s almost exactly the same size as our home world. This marks the first time researchers have used Webb to confirm an exoplanet. https://t.co/hX8UGXplq2 #AAS241 pic.twitter.com/SDhuZRfcko
— NASA Webb Telescope (@NASAWebb) January 11, 2023
As the agency notes, among the telescopes operating today (both ground-based and orbital), only JWST has the resolution that allows you to accurately characterize the atmospheres of Earth-type exoplanets. The research team has not yet determined what, if any, atmosphere LHS 475b has.
“Counterintuitively, a 100% carbon dioxide atmosphere is so much more compact that it becomes very challenging to detect,” Lustig-Yaeger said.
However, scientists are sure that the new exoplanet cannot have a thick atmosphere dominated by methane, similar to the atmosphere of Saturn’s moon Titan:
There are some terrestrial-type atmospheres that we can rule out,” explained Lustig-Yaeger. “It can’t have a thick methane-dominated atmosphere, similar to that of Saturn’s moon Titan.”
The surface of LHS 475b has a temperature several hundreds of degrees higher than on Earth. So, if cloud cover is discovered in the course of further research, the new planet is more likely to be closer to Venus than to Earth. The researchers also confirmed that the planet orbits in just two days and is closer to its star than any other planet in the Solar System. But the red dwarf star LHS 475b has a surface temperature half that of the Sun, so researchers hope it may still have an atmosphere.