From a post to sci.astro.research, April 12, 2001, by Marshall Perrin
Paul Stowe
The Voyager 2 IRIS results for Uranus are 34+-38 erg/cm^2/s.
The values for Neptune are 433+-46 erg/cm^2/s.
See
Yes, see
Bergstrahl & Miner 1991
(_Uranus_, Univ. Ariz. Press)
and
citations therein. Current models of He rain agree well
with the observed depletion of He in the atmosphere of Saturn, and the
smaller but still noticeable depletion in Jupiter.
I wrote a literature review paper for my graduate planetary astronomy
seminar last fall, focusing on the question of why the value for Uranus
is so much less than the other gas giants. There are a couple strong
theories floating around, mostly having to do with restriction of
convection in the interior of Uranus relative to the other giant
planets, but the available data isn't yet strong enough to be entirely
conclusive. The paper is available at
Take a look - it summarizes the general physics involved in planetary
internal heat sources and has a pretty extensive bibliography to get you
started digging for more.
Don't know anything about this one, sorry.
> I have a few questions pertaining to the gas giant planets.
>
> First, it is my understanding that Jupiter emits a total of 2 times the
> thermal energy that it receives from the Sun [6.8 x 2 or ~13.6 watts/m^2],
> Saturn 2.3 times as much [2 x 2.3 or ~ 4.6 watts/m^2], Uranus and Neptune
> are less well defined.
> Could someone confirm the Jupiter/Saturn values above, and give good
> values for Uranus and Neptune? References would be appreciated.
> Second, Saturn's excess is said to be due to Helium rainout. Has there
> ever been a calculation as to how much (in-falling mass), and how long
> such must and could be sustained, before He depletion occurred?
> Finally, a similar question for the proposed carbon rainout on Neptune?