Astronomy: Surprising evidence of an atmosphere around a too-hot rocky planet
The most convincing evidence to date of a dense atmosphere around a rocky planet outside the solar system has been found in an unexpected place.
(Image: NASA, ESA, CSA, Ralf Crawford (STScl))
A research group has discovered the clearest evidence to date of an atmosphere around a rocky planet outside the solar system in an unexpected location. The team led by Johanna Teske from the Carnegie Institution for Science found it on the ultra-hot exoplanet TOI-561 b, which is expected to be covered by a magma ocean, explains the research institution. Originally, it was assumed that it was too small and too hot to retain an atmosphere, but observations with the James Webb Space Telescope suggest that it has succeeded in doing just that. Otherwise, it would be difficult to explain why it is almost 1000 degrees Celsius cooler than it should be given its orbit.
(Image:Â NASA, ESA, CSA, Ralf Crawford (STScl))
TOI-561 b orbits its star once every approximately 10.5 Earth hours at a distance equivalent to one-fortieth of the distance between the Sun and Mercury. Therefore, it is tidally locked, meaning it always shows the same side to its star, which heats up extremely. If it were a bare rocky planet, the temperature there would have to reach 2700 degrees Celsius, the team writes. Instead, measurements with the James Webb Space Telescope's Near-Infrared Spectrometer (NIRSpec) showed only 1800 degrees Celsius, still extremely hot but significantly cooler. This could only be explained by the presence of a dense atmosphere that can effectively transport heat to the eternal night on the far side, says the group.
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How an exoplanet in this extreme environment managed to retain its atmosphere is now the next big question. The immense radiation should have removed it long ago. Answering this now will be extremely exciting, says Teske. To achieve this, further data collected during a total of 37 hours of observations of the system will be evaluated first. This allows, among other things, the temperatures across the entire exoplanet to be determined, thus narrowing down the composition of the atmosphere. The current findings are presented in a scientific article in The Astrophysical Journal Letters.
(mho)
