Gas giant planets make up about 15% of the more than 5000 extrasolar planets detected to date. To characterize them in more detail and to learn how they were formed and evolved it is absolutely necessary to know masses and radii of the planets and thereby to determine their densities.
The solar system gives us orientation: Earth and Jupiter have densities of 5.5 g/cm³ and 1.3 g/cm³, respectively. Olga Zakhozhay and her team at MPIA in Heidelberg, including SPP-funded Gabriel Marleau, found a very young planet around a solar-like star with unexpected parameters:
The size of HD 114082 b is about that of Jupiter, but its mass is eight times larger which ends up with a density twice that of the Earth. But Earth is a rocky planet with an iron-nickel core, whereas Jupiter is made of hydrogen and helium, the lightest elements in the universe.
Taking in two account that HD 114082 b is a very young planet the explanation is not apparent. How did the plant which orbits its central star in 110 days formed? The preferred models don’t fit.
The result is based on a radial velocity survey spanning 4.5 years with the 2.2-metre telescope operated by MPIA at La Silla. In addition to the RV measurements a single transit event in the TESS data revealed the size of HD 114082 b. In combination of both methods the bulk parameters of the planet could be evaluated. HD 114082b is currently the youngest known giant planet with an established mass and radius.
Find the original publication here.
Image Credit: NASA/JPL-Caltech