Astronomy: "Exotic" atmosphere of a "bizarre" exoplanet raises questions
PSR J2322-2650b orbits a pulsar and can therefore be studied particularly precisely. Its composition cannot currently be explained.
Artistic representation of the elongated exoplanet and its star
(Image: NASA, ESA, CSA, Ralf Crawford (STScI))
The James Webb Space Telescope has discovered an exoplanet with an “exotic” atmosphere. The envelope of the celestial body, designated PSR J2322-2650b, is dominated by helium and carbon, and deep within the atmosphere, soot clouds could condense into diamonds. NASA reports, adding that the detection of molecular carbon there is “very unusual.” The finding suggests that there is almost no oxygen or nitrogen. At the same time, it is so close to its massive star that it is stretched into a “strange lemon shape” by its gravity.
The star is also “completely bizarre”
As the researchers further explain, it is not only the exoplanet that is unusual. The star it orbits is also “completely bizarre,” as Michael Zhang of the University of Chicago puts it. It is a millisecond pulsar, an extremely rapidly rotating neutron star with the mass of the sun but only the size of a city. Because it primarily emits gamma rays and high-energy radiation, which the James Webb Space Telescope cannot detect, the exoplanet can be studied particularly well. Therefore, a “flawless spectrum” was analyzed, which allowed for a much more detailed investigation than is the case with other exoplanets.
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How the exoplanet acquired its unusual composition is completely unclear. Molecular carbon is normally bound by all sorts of atoms present in an atmosphere. Therefore, the exoplanet could not have formed in a normal way, says Michael Zhang of the University of Chicago, who led the analysis. It is also difficult to imagine that we are seeing the remnant of an exoplanet whose outer atmosphere was stripped away by the star, because even then the carbon could not be explained. Co-author Roger Romani of Stanford University is therefore delighted to “learn more about the oddities of this atmosphere.” The team presents its findings so far in the Astrophysical Journal Letters.
(mho)
