Quote:
Originally posted by astro_kct@Sep 9 2004, 08:27 PM
Please tell me more about your statement that the planet must be hydrogen-rich: I don't think that the facts strictly make that a necessity.
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You quoted eburacum45, but I'll provide some answers.
It is not a necessity that the planet be Hydrogen rich, but it seems likely based on things we know:
-The planet has a mass about 5 times that of Jupiter
-The photosphere star has about 1/4 the concentration of heavy elements as our sun
-If the planet were made only of heavy elements, it would contain more mass of heavy elements than the star it orbits [pretty unlikely scenario]
-As John L points out, even if it didn't start with a heavy atmosphere, a ball of rocks and Iron that heavy would acquire one.
BTW, it is generally assumed that planets more massive than Jupiter have roughly the same radius as Jupiter, but are simply more dense in the center.