For the first time, the uncovered nucleus of an exoplanet has been discovered, which allows an unprecedented view into the interior of a planet. Bern researchers are leading the interpretation of the most astonishing phenomenon.
The newly discovered Exoplanet TOI 849 b is something very special in many ways. For example, it orbits very close to its star – which, by the way, is very similar to our sun – so close that a year on it only lasts 18 hours and the surface temperature is 1,500 degrees Celsius.
In addition, TOI 849 b has a very high density: It is about 40 times as heavy as the earth, but its radius is only slightly more than three times that of our planet. “There are no known planets with this mass that have such a short orbit around their star,” said David Armstrong of the Department of Physics at the University of Warwick (GB), who heads the study on the “stripped” exoplanet.
Intact, exposed core
Christoph Mordasini from the Physics Institute of the University of Bern played a leading role in the theoretical interpretation of the discovery. “For such a massive planet, such a high density or such a small proportion of hydrogen and helium is very surprising,” says Mordasini. “With such a mass, one would expect that the planet would have attracted a lot of hydrogen and helium during its formation in the protoplanetary disk.”
But these gases are not there. “This suggests that TOI 849 b is an exposed planetary nucleus,” says Armstrong. “It is the first time that an intact, exposed core of a gas giant has been discovered around a star.”
The question now is: How did the now naked gas giant lose his “robe”? Or has he never had one? The ball for the interpretation lies at the University of Bern, where the “Bern Model of the Formation and Development of Planets” has been continuously developed since 2003. On the basis of this model, two theories can be formulated, as Mordasini announced on Tuesday: either the shell was lost or it never existed.
Failed gas giant?
“The first is that the exoplanet was once similar to Jupiter, but” lost “almost all of its external gas due to various influences,” said Mordasini. This could have happened due to tides where the planet’s shell is torn apart because the planet is extremely close to its star, or even because of a collision with another planet. Large-scale evaporation of the atmosphere could also play a role, but cannot be held responsible for all of the “lost” gas alone.
Alternatively, TOI 849 b could be a “failed” gas giant. “Once the nucleus was formed, something could have been completely different than normal, and the nucleus never formed a massive atmosphere as usual. This could have happened if there was one in the protoplanetary disk from which the planet was formed Would have created a gap in the gas because of the gravitational interaction with the planet or if the material in the disc had run out at the point where gas accretion normally follows, “said Mordasini. (apa)
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