It is small, light and fast, but at the same time extremely dense: The exoplanet GJ 367b is certainly one of the most astonishing celestial bodies among the exoplanets that are not poor in exotics. Kristine Lam from the Institute of Planetary Research at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) and her team presented it in Science.
GJ 367b circles its star, a red dwarf at 31 light years away from Earth and is only a little larger than Mars. This makes it one of the smallest and half an earth mass also one of the lightest exoplanets that you have been able to prove so far. At the same time, it is extremely compact and has a density almost like pure iron. He only needs almost eight hours to surround his mother star, while Merkur needs a full 88 days in our solar system.
"GJ 367b can certainly be classified as a rock planet from the exact determination of radius and mass," says Lam. "It is reminiscent of Mercury in size and composition and is one of the terrestrial planets." And that brings research into a step forward in search of a "second earth", according to the astronomer.
Due to its extremely short orbital period, the celestial body belongs to the "ultra-short-period planets" (USP), the origin of which is still unknown. It was discovered by the transit method, which measures minimal differences in brightness in the star's light as the planet passes by it. It is one of the most common methods in the search for exoplanets, which in this case was detected with the help of NASA's TESS space telescope.
The high density of GJ 367b suggests that the exoplanet has a large iron core. "These properties are similar to those of Mercury, which, with its disproportionately large core of iron and nickel, differs from the other terrestrial bodies in the solar system," says Szilárd Csizmadia from the DLR. Since the planet revolves very close to its star, it is exposed to much higher radiation: more than 500 times as strong as the earth. Its surface temperature could be up to 1500 degrees Celsius, a temperature in which many rocks and metals melt.
The planet circles a red dwarf, no red giant. We corrected the mistake.
