Can a Spherical Object in Space Achieve Fusion Without External Forces?

[barycenter]

At what mass (if any) could a perfectly spherical, stationary object, without the influence of external gravitational forces, achieve fusion in space? Why/why not? What would, or would not, be the outcome of the sphere? Please supply link(s) to additional information.

 

[xlines]

At what mass (if any) could a perfectly spherical, stationary object, without the influence of external gravitational forces, achieve fusion in space? Why/why not? What would, or would not, be the outcome of the sphere? Please supply link(s) to additional information.

Yes, it's possible, limit is around 10% of mass of Sun. Additional information :
http://en.wikipedia.org/wiki/Star

 

[barycenter]

xlines, thanks for replying. I do have a follow up question though. If you believe a mass about 1/10th the size of the Sun can achieve fusion, than why aren't there any signs of fusion coming from Jupiter?

As for the link to Wikipedia, I'm not too sure about their credibility, but I will check to see if their references hold water. I look forward to your follow-up answer.

 

[murray92]

I think I recall that the limit for H-He fusion is about 50 times Jupiter masses (or something of that oderer of magnitude.)

And brown dwarfs are just 10 times more massive than jupiter.

 

[Drakkith]

Remember that deuterium, and to a lesser extent tritium, also exist in other planets and stars. A collapsing mass of matter could be massive enough to ignite D-D fusion but NOT P-P fusion. I think I read somewhere that Jupiter itself MIGHT have a small amount of fusion reactions going on thanks to this. (But take it with a grain of salt, as I have no idea where I heard that from)

 

[xlines]

xlines, thanks for replying. I do have a follow up question though. If you believe a mass about 1/10th the size of the Sun can achieve fusion, than why aren't there any signs of fusion coming from Jupiter?.

Well, having only one in thousand mass of Sun, Jupiter is below stated limit. As far as I recall, Jupiter emits much more energy that it receives from Sun, but I can't claim it is fusion in origin. I recall vaguely that it has something with converting gravitational potential energy of helium droplets falling to heat or something ...