Researchers at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, confirmed that NASA’s James Webb Space Telescope has detected an exoplanet (extrasolar planet) that is 99% the diameter of Earth, formally classified as LHS 475. b and located 41 light years away, in the constellation of Octans (the Octant, in Latin). The team of researchers chose to observe this target with the Webb telescope after carefully reviewing the targets of interest from NASA’s Transiting Exoplanet Survey Satellite (TESS), which hinted at the existence of this planet.
Webb’s Near Infrared Spectrograph (NIRSpec) captured the planet easily and clearly with just two observations of its transit. “There is no doubt that the planet is there. Webb’s impeccable data validates this,” said Jacob Lustig-Yaeger, a member of the team. Based on data collected by the telescope, LHS 475 b is a few hundred degrees warmer than Earth, so if clouds are detected, researchers may conclude that the planet is more like Venus, which has an atmosphere of carbon dioxide and is perpetually shrouded in thick clouds.
Among all the operational telescopes, only the Webb is capable of characterizing the atmosphere of Earth-sized exoplanets. The team of researchers tried to assess what is in the atmosphere of this planet by analyzing its transmission spectrum.
Although the data shows that it is an Earth-sized planet, it is not yet known if it has an atmosphere. “The telescope is so sensitive that it can easily detect a variety of molecules, but we still can’t draw any definitive conclusions about the planet’s atmosphere,” said Erin May, also of the Johns Hopkins University Applied Physics Laboratory.
Although the computer cannot conclude about what is present, it can definitely tell what is not present. “There are some terrestrial-type atmospheres that we can rule out,” Lustig-Yaeger explained. “It cannot have a dense methane-dominated atmosphere, similar to that of Saturn’s moon Titan.” The team also noted that while the planet may not have any atmosphere at all, there are some atmospheric compositions that have not been ruled out, such as an atmosphere of pure carbon dioxide.
Even more precise measurements are required for the team to be able to distinguish an atmosphere of pure carbon dioxide from no atmosphere at all. The researchers are scheduled to obtain additional spectra with upcoming observations this summer. 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 planet in our solar system, its red dwarf star is less than half the temperature of the Sun, so researchers project it could still have an atmosphere. The team’s results were presented at an American Astronomical Society (AAS) press conference on Wednesday, January 11, 2023.
Sources: www.cubadebate.cu
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