Fraction of incident flux that escapes from a star

[ppy]

If the flux entering such an atmosphere from the core of the star at a radius is r0 is F0,
the flux that reaches radius r is given by

F(r)=F0*e^k(r^-2-r0^-2)

where k is a constant

a) Write down a formula for the fraction of the incident flux that escapes from the star
entirely. {3}
b) If 50% of the flux escapes from a star where the base of this stellar atmosphere lies at a
radius r0, what percentage of the flux escapes if this atmosphere only starts at twice as
large a radius? {3}



Is the answer to (a) just F=F0*e^k(R^-2-r0^-2) where R=radius of star and then to find the fraction you just do F(R)/F(r)?

Thanks :)

 

[Nate810]

Yes, that is correct. To answer part (b), you can use the same formula and plug in twice the radius for R. Then, the fraction of the flux that escapes is F(2R)/F(r).