From: shoham@ll.mit.edu (Daniel Shoham)
Newsgroups: rec.arts.sf.starwars
Subject: Re: More CHALLENGING QUESTIONS-IF YOU DARE!!!
Date: 15 Nov 92 21:53:00 GMT
Article-I.D.: ll.1992Nov15.215300.21464
Organization: MIT Lincoln Laboratory

In article <92319.161643DCC117@psuvm.psu.edu> DCC117@psuvm.psu.edu writes:
>In article <1992Nov14.000931.867@ll.mit.edu>, shoham@ll.mit.edu (Daniel Shoham)
>says:
>>
>>In article <1992Nov13.104755.10686@cs.hw.ac.uk> adrian@cs.hw.ac.uk (Adrian    )
>>Hurt
>>writes:
>>>
>>>Here's the chance for the real astronomy experts out there to flame me, but:
>>>Could the Death Star's big gun ignite a gas giant and turn it into a star?
>>
>>I am not a real astronomy expert (I only play one on the net :-), but I think
>>I can help out.
>>
>>It is oft stated that gas giants (like Jupiter) are miniature stars that have
>>never ignited. While, strictly speaking, this is true; it does *not* follow
>>that all it takes is to "ignite" them to create a star. The core of a gas
>>planet, as well as the core of a star is maintained at a pressure that is
>>balanced by the compeating forces of gravity (trying to compress the core) and
>>of thermal activities (trying to expand the core). Thermo-nuclear reactions
>>(fusion - what powers stars) take place at *any* pressure, but are more likely
>>(and hence happen more often) at higher pressure (and temprature). {On Earth,
>>the temprature and pressure are very low by the fusion standards and the
>>probability of a reaction taking place is too low to be observable (except
>>at the core of hydrogen bombs, in fusion research reactors, and certain Utah
>>laboratories).} The pressure at the core of a gas giant is sufficient for
>>some non-negligable energy production via fusion. In fact, Jupiter generates
>>more energy than it receives from the sun. If for some reason, a temporary
>>increase in the pressure/temprature of part (or even the entire) core were
>>to occur (it does not matter what caused it - a statistical fluctuation, a
>>Galileo-like atmospheric diving probe with an H-bomb, or the big guns of the
>>mighty deat star), the reaction rate would temporarily increase. The increased
>>energy production will cause an expension of the excited core region. That in
>>turn will reduce the pressure (and temprature) and with it the rate of energy
>>production. The excited region will thus cool, allowing gravity to restore
>>the region to it's original size and energy production level. In short, the
>>balance will self-restore (the actual mechanics is somewhat more complex, but
>>this is the general idea).
>
> How does this affect the plausibility of Dave Bowman's conversion of
>Jupiter into the "sun" Lucifer in 2010?
>
 
Simple: it is not plausible. To turn Jupiter into a "sun", you need to add
more mass (specifically hydrogen) to generate the needed gravitational
compression to keep the fusion going. Unless the aliens have actually done
that (I suppose you could argue that to have been the case) in 2010, or unless
they know of physics that allow the formation of stars other than the ones
we know about - they could not have "ignited" Jupiter.

Dan Shoham               shoham@ll.mit.edu
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