Jupiter as a Star?



name         David
status       educator
grade        other
location     IL

Question -   With a heat factor which is expanding, and
therefore gas compression and molecular restructuring, which is
said to have occurred -igniting our sun,  is it a possibility,
over time, Jupiter could emerge or ignite as a star?
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I think the only way that this would be possible is if jupiter was able
to consume a good deal more mass.  Without an ample enough food source,
I believe it will stay as it is and the fusion process will not occur.
Astronomers have already found objects outside our own solar system that
are larger than jupiter, but that appear to just be planets. The
theoretical limit is something around 80 times the current mass of
Jupiter.  So indeed, the food source would need to be quite large(or
perhaps it would then be better to think of Jupiter AS the food source
for the other object).
And even if an object has enough mass, it also requires that enough of
the mass is in a small enough area at the same time.  So, 80 times as
massive, and hot and dense.

However, all that aside, Jupiter already shines!  It just doesn't happen
from the fusion process. I believe Jupiter already radiates more
energy(most of it in the infrared spectrum) than it receives from the
sun.  Now, that's really not terribly surprising when you think of the
fact that A) all those winds, storms, and (compared to earth) immense
gravity on Jupiter are going to give off energy and B) even though
Jupiter is large relative to the other planets, this is offset by its
distance from the sun.

For the truly ambitious, you can listen to Jupiter!  Jupiter radiates at
around 20MHz I believe.  There are fairly simple kits available from
NASA (and I believe the plans/schematics are free) that will allow you
and your students to listen to Jupiter.  Look up "Radio JOVE" for more
details.

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Michael S. Pierce
Materials Science Division
Argonne National Laboratory
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David,
Jupiter does not have anywhere near the mass needed to form a 
star.  The Sun has about 99.8% of the mass of our solar system in it 
and Jupiter contains most of the rest.  That being said, the sun is 
still 1050 times heavier than Jupiter.  The mass needs to be very 
high so that fusion can start and Jupiter would need to weigh a 
minimum of 80-100 times what it currently weighs in order to start fusion.

Matt Voss
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David,

While it is nice to imagine an era with two suns (me being a fan of 
Arthur C. Clarke) Jupiter simply does not have enough mass to 
sustain a fusion reactor in its core. Think of it this way, a fusion 
reaction (which is what powers a star) is an explosion, the heat 
from the reaction will cause the proto-star's matter to expand away 
from the reaction. Thus, the nuclear fuel (hydrogen, deuterium, 
tritium) would actually get blown away from the explosion. The 
reason a star can sustain a nuclear reaction (keep the fuel within 
the reacting core) is that its mass compresses the atoms at its core 
so that an equilibrium between the nuclear reacting core and the 
expansion of the heated matter is formed. Jupiter is 1/80th the mass 
of the Sun, it simply does not have enough mass to keep a nuclear 
fusion reaction going.

Greg (Roberto Gregorius)
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