For the first time, the James Webb Space Telescope has confirmed the presence of an exoplanet, LHS 475. JWST observations reveal a rocky world, which could have an atmosphere.
It is a small, rocky exoplanet orbiting its star 41 light-years away in the constellation Octant. It is a bit special, because it is the first identified thanks to the James Webb telescope. More than a year after its launch into space, the JWST has reserved this new surprise for us to start 2023.
An Earth-sized exoplanet
For the first time, the existence of an exoplanet was thus confirmed with James Webb, let it be known NASA on January 11. This new world is called LHS 475 b. What do we know of him? This exoplanet is almost the same size as the Earth, very exactly 99% of its diameter (as a reminder, the Earth’s diameter is 12,756 km).
The planet is also known to be barely warmer than Earth (a few hundred degrees warmer), which could make it closer to Venus (heated to a constant temperature of 450°C). The exoplanet evolves very close to its star: it needs just 2 days to complete an orbit. That said, as the star LHS 475 is cooler than the Sun, it is not impossible that the exoplanet has an atmosphere.
How did James Webb find LHS 475 b?
James Webb was not used alone by scientists to detect LHS 475 b. It was first the observations of another telescope, TESS (“Transiting Exoplanet Survey Satellite”), which made it possible to suspect the presence of this star.
The transit method is one of the best-known detection methods for exoplanets. This is a so-called indirect method. It consists in detecting the occultation of a star, when the exoplanet passes in front of it.
But, it still remained to confirm its existence. The area was then targeted by James Webb. The telescope was able to confirm the presence of the exoplanet using the transit method. With only 2 transits of LHS 475 b in front of its star, the JWST was able to verify the observations of TESS.
Despite the confirmation permitted by James Webb, we still have a lot to learn about LHS 475 b. We know it’s a small rocky ball. However, scientists still have no idea if it has an atmosphere, and what that atmosphere might be made of. This is why it is already planned to observe the exoplanet again during the summer of 2023.
