RE: Supersized rocky planets are out there.
June 3, 2014 at 1:43 pm
(This post was last modified: June 3, 2014 at 1:56 pm by Anomalocaris.)
I believe the current consensus is all the gas giants in our solar sytem have solid cores of heavy elements. The core of Jupiter, if stripped bare of the overlying hydrogen and helium mantle, would be similar, perhaps somewhat larger and denser, compared to this newly discovered "mega"earth.
Hence my speculation about this megaearth being the stripped core of a former gas giant.
The problem is current model have a hard time accummulating enough rocky material in the inner portion of a protoplanetary disk to form a bare rocky planet as large as Kepler 10c around a roughly solar massed star. If so large a rocky planet were to form further out in the protoplanetary disk then it would also capture a very large inventory of gaseous or icey material, so it would end up as either a gas giant or a ice giant with a rocky core buried in the middle. So it is not easy to postulate a trajectory that would lead to so large a bare terresterial planet without postulaing either a gas giant forerunner to this giant terresterial planet, or some very unusual evolutionary history for the original protoplanetary nebula.
If the central star was much more massive, say 20 times the mass of the sun, then it becomes easy to form huge bare terresterial planets in the protoplanetary nebula. In fact, around very large protostars, it is possible to form rocky planets with the masses as large as the largest possible gas giants.
Hence my speculation about this megaearth being the stripped core of a former gas giant.
The problem is current model have a hard time accummulating enough rocky material in the inner portion of a protoplanetary disk to form a bare rocky planet as large as Kepler 10c around a roughly solar massed star. If so large a rocky planet were to form further out in the protoplanetary disk then it would also capture a very large inventory of gaseous or icey material, so it would end up as either a gas giant or a ice giant with a rocky core buried in the middle. So it is not easy to postulate a trajectory that would lead to so large a bare terresterial planet without postulaing either a gas giant forerunner to this giant terresterial planet, or some very unusual evolutionary history for the original protoplanetary nebula.
If the central star was much more massive, say 20 times the mass of the sun, then it becomes easy to form huge bare terresterial planets in the protoplanetary nebula. In fact, around very large protostars, it is possible to form rocky planets with the masses as large as the largest possible gas giants.