Jeremy Watts wrote:
"Starlord" wrote in message
...
Are you talking about a Jupiter type planet or a rockry planet? Becuae the
rockry planet would never reach the point where it would become a star.

As far as a Jupiter type planet to reach even the level where it would
become a dim short lived R.D. star it would be somewhere around 25 jupiter
mass. To become a star like our own, it would never be a planet at all, it
would be a cloud of gas that would be compressed under it's own g force to
the point where the fushion reaction would start and thus a star is born.

yeah i may be getting confused here with the mass limit for a black hole,
but i just seemed to remember there was a name for a hypothetical mass limit
beyond which a star would be formed.


The current IAU position on the borderline between 'planet' and 'brown
dwarf star' is around 13 Jupiter masses (or 2.4687*10^28kg) for bodies
with metalicity like our sun.

IIRC anything under about 0.1 solar masses (or 1.981*10^29kg) can't fuse
hydrogen, and only burns isotopes like Deuterium, and that is considered
the upper range of 'brown dwarf' starts and the bottom range of 'red
dwarf' stars.

So the approximate ranges a 13 jovian masses is a planet, 13 - 100
jovian masses is a brown dwarf star, and somewhere over 100 jovian
masses (0.1 solar masses) it begins burning hydrogen and is a red dwarf
star.

The mass of the Sun is 1.9891*10^30kg, and the mass of Jupiter is
1.899*10^27kg, so the sun is about 1,047 jovian masses.


[snip]

--
Bill Hudson