The exoplanet LHS 475 bi its star (Illustration). Credit: ESA
Ibadan, 13 January 2023. – Researchers have confirmed the presence of an exoplanet, a planet orbiting another star, using the NASA/ESA/CSA James Webb Space Telescope for the first time. Formally classified as LHS 475 b, the planet is almost exactly the same size as Earth, at 99% of Earth’s diameter.
Kevin Stevenson and Jacob Lustig-Yaeger led the research team that made the discovery, both from Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland. The team chose to observe this target with Webb after carefully reviewing data from NASA’s Transiting Exoplanet Survey Satellite (TESS) that hinted at 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 this,” Lustig-Yaeger said. The team tried to assess what is in the planet’s atmosphere by analyzing its transmission spectrum. Although the data show that it is “an Earth-sized terrestrial planet, they still don’t know if it has an atmosphere. While the team can’t yet conclude what’s present, they’re sure what’s absent.”
“There are some Earth-type atmospheres that we can rule out,” Lustig-Yaeger explained. “It cannot have a thick atmosphere dominated by methane, similar to Saturn’s moon Titan.” The team also notes that while the planet may not have an atmosphere, there are some atmospheric compositions we haven’t ruled out, such as an atmosphere of pure carbon dioxide.
Webb also revealed that the planet is hundreds of degrees warmer than Earth. Therefore, if the researcher detects clouds, he can conclude that the planet is more like Venus. This is because the planet has a carbon dioxide atmosphere with thick clouds perpetually surrounding it. 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.