Red spot + Jr. (APOD 25 Jul 2006)

Martin · Post by **Martin** » Tue Jul 25, 2006 2:11 pm

Is there even a remote chance that Jupiter could at some point go nuclear

orin stepanek · Post by **orin stepanek** » Tue Jul 25, 2006 4:20 pm

I don't think so unless it gains in mass quite a bit. If it does I guess the solar system would become a binary system. I wonder how that would affect the weather. Probably speed up global warming.

http://antwrp.gsfc.nasa.gov/apod/ap060725.html

http://www.galactic-guide.com/articles/2S39.html

Orin

BMAONE23 · Post by **BMAONE23** » Tue Jul 25, 2006 4:49 pm

We would certainly get more daylight hours over a 6 year cycle then brighter days for a 6 year cycle

Qev · Post by **Qev** » Tue Jul 25, 2006 6:33 pm

The current estimate for the minimum mass of an object to sustain a fusion reaction (ie. become a star) is something around 75 Jupiter masses. So good ol' Jupiter will probably be hanging around with us for a long time yet.

Martin · Post by **Martin** » Tue Jul 25, 2006 7:32 pm

This makes sense to me however, is mass the only determining factor. Could mass be replaced with something else as the trigger?

Qev · Post by **Qev** » Tue Jul 25, 2006 8:57 pm

Not for a sustained nuclear reaction, no. A would-be star needs enough mass, and thus enough gravity, to compress the matter at its core to the point where fusion reactions can occur, and maintain those conditions despite the outward forces of the radiation pressure generated by fusion. It's a balancing act. Jupiter's gravity is too weak to compress the core to the point where fusion can be sustained.

It's thought that some brown dwarf objects, near the minimum stellar mass, have enough internal pressure to undergo deuterium fusion, which has a lower threshold than proton-proton fusion used by typical low-mass stars.

Martin · Post by **Martin** » Wed Jul 26, 2006 12:26 pm

Thx Qev.

What my line of thought was....It seems stars come in so many different sizes that maybe there were other factors besides mass that would start a nuclear ignition.

Now my question is about super massive stars. How did they get to be so super massive without going nuclear earlier in their life -once the mass threshold was reached

Qev · Post by **Qev** » Wed Jul 26, 2006 5:18 pm

From what I gather, there are two main competing theories of high-mass star formation (it's apparently not well-understood at this point). One is that they form much like low-mass stars, through accretion of matter, albeit at a much faster rate of accretion. The other is that they're formed by the coalescense of several lower-mass protostars.

Currently observations seem to support the first theory over the second, but it's not without problems. As you've pointed out, a forming high-mass star tends to throw out a lot of radiation, which can ionize and blow away the very gas that its growing from, limiting its growth. This limiting factor is probably why stars larger than about 8 solar masses are relatively rare.