Look I’ve been up for 29 hours so my math is probably off but if something is 4x the diameter and 10x the mass of earth, it would be just way too dense to be made of anything other than, like, solid metal.
So I went and looked at the academic paper and they never even mention it being 4x the size of earth. The caltech news article that I pulled up (remember these researchers are from caltech) never mention a 4x size number either. I have no idea where The Guardian got that number, but I found the Washington Post mentions it too, but it’s never mentioned anywhere in any scientific news sources, so I’m disregarding it entirely.
The only thing mentioning the possible dimensions in the academic paper is that it’s between 1 and 10 times the mass of Earth.
Because the only thing we have is mass, there’s no way to determine density or that it’s a rocky planet like people seem to default it to.
Logically, it would probably be a gas giant similar to both Uranus and Neptune. Uranus is 15 earth masses and Neptune is 17 earth masses. It would probably have a very similar composition with a miles thick atmosphere, then underneath that, miles and miles of ice, and below that, a tiny rocky core.
So from that, and because the rocky core is actually quite small, (most likely smaller than that of Earth) it probably isn’t geothermally active anymore.
