Did TOI 849 b lose its outer layers?
One possible explanation of the missing outer layers of TOI 849 b is that it was somehow stripped violently from the planet.
“There are several possibilities explaining how TOI 849 b became this exposed core which can be split into two categories,” Mordasini explains. “The planet had once a much more massive envelope of H/He, but it somehow lost it. Or The planet never had a lot of H/He.”
The stripping of the outer layers of TOI 849 b transforming it from a gas giant to an exposed planetary core can be further divided down into two distinct sub-scenarios. “Firstly, perhaps during the formation phase, the orbit of the planet could have been very eccentric. When it got circularised via a tidal interaction with the host stat, the energy was injected into the planet, leading to the ejection of some or all of the gaseous envelope,” says Mordasini. “Alternatively, the gaseous envelope could have been ejected because of a giant impact or collision with another protoplanet also originally present in the system of TOI 849 b.”