Mass of star



I have posted about this before, both to sci.physics
and sci.math, but I didn't get any answers,
so i decided that i should try this more serios group.

Also I appoliges for my poor english.

Here is the question:
Suppose you have a star with constant temperature in
the whole volym, and that boyles law holds for the gas.

Let P(r) bee the pressure at distance r from the stars
center of mass.
And M(r) the mass out to r from the center of mass.

THEN:
P'(r)=-P(r)M(r)/r^2
M'(r)=P(r).r^2

And M(0)=0

I have choicen the units to make the equation look good.
What is the limit of M(r) as r go to infinity.
It' seems like it must go to infinity.
Can somone prove this?


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