James Webb Space Telescope discovers its first exoplanet
The James Webb Space Telescope has discovered its first planet orbiting a star other than our sun. This is planet LHS 475 b, which is located at a distance of 41 light-years in the Octant constellation, at the southern celestial pole.
The research team from the American Johns Hopkins University Applied Physics Laboratory say that the planet has a diameter that is 99 percent that of our Earth. According to the researchers, it is impressive that James Webb was able to also discover such a small, rocky planet: “These first observation results of an Earth-sized rocky planet open the door to many future possibilities for studying the atmosphere of Rocky Planets with James Webb.”
The team began deploying the James Webb telescope after looking at potential exoplanet candidates based on data from the Transiting Exoplanet Survey Satellite. Based on data from that satellite, it was already expected that LHS 475 b existed, but this was only definitively determined with the data from James Webb. This was done with the Near-Infrared Spectrograph or NIRSpec, an advanced spectrograph that forms one of the four scientific instruments on board the telescope.
The existence of LHS 475 b has been determined using the well-known transit method, which looks for small variations in the light coming from a star, which could be caused by a planet blocking a small amount of light in its orbit around the star as it passes in front of the star. star slides by. In the case of LHS 475 b, the latter took place on August 31 last year.
The planet is a few hundred degrees warmer than Earth. LHS 475 b orbits its star in just two days and is very close to its star, but the star is a red dwarf that reaches less than half the temperature of our Sun, leading the researchers to believe that the existence of an atmosphere is not directly excluded. If clouds are eventually discovered, the conclusion could be that the planet resembles Venus.
James Webb is suited to determine whether an atmosphere is present and what it consists of, but in this case scientists cannot yet say whether there is an atmosphere. They say that the data is ‘beautiful’ and that a multitude of different molecules can easily be detected, but that no definitive conclusions can yet be drawn from it.
The research team cannot yet say what is present, but they can say what is not present. This means that there cannot be a thick atmosphere with mostly methane, as is the case with Saturn’s moon Titan. It is possible that LHS 475 b has no atmosphere, but the researchers acknowledge that certain atmospheric compositions have not yet been ruled out, such as an atmosphere with only carbon dioxide. Such a composition is very compact and makes it difficult to detect. More observations will follow in the coming summer to take additional spectra.