Are Small Rocky Worlds Naked Gas Giants?

astroengine writes "The 'core accretion' model for planetary creation has been challenged (or, at least, modified) by a new theory from University of Leicester astrophysicists Seung-Hoon Cha and Sergei Nayakshin (abstract). Rather than small rocky worlds being built 'bottom-up' (i.e. the size of a planet depends on the amount of material available), perhaps they were once the cores of massive gas giant planets that had their thick atmospheres stripped after drifting too close to their parent stars? This 'top-down' mechanism may also help explain how smaller worlds were formed far from their stars only to drift inward toward the habitable zone."

Re:Hot Jupiters?

[GreenTom]

RTFA (A=abstract, since the article is behind a paywall)...the abstract doesn't say that gas giants formed, then were stripped. It suggests the protoplanatary disk breaks up into clumps of gas and dust, and that the clumps that come too close to the star are stripped of their gas. I think all this happens long before the dust clouds condense into planets. At least from the abstract, all they seem to be saying is that the same original dust clouds could become rocky planets or gas giants, depending on if they're disrupted or not.

Re:Hot Jupiters?

[arcctgx]

RTFA (A=abstract, since the article is behind a paywall)

Never fear, arXiv delivers: http://arxiv.org/abs/1010.1489 [arxiv.org]

Re:Highly unlikely theory

[gstrickler]

I read the article and the abstract. Apparently you failed to comprehend it, go read it again. They talk about stripping the atmosphere/gases from a 7.5 Earth Mass (Me) clump at ~8 AU. So, my example still applies. The details may vary a bit, but a 7.5Me clump is going to have a significant gravity well/escape velocity, and for it to absorb enough solar radiation @ ~8 AU is beyond unbelievable, the math just doesn't work.