Degeneracy pressure of a White Dwarf Star

[tanaygupta2000]

Homework Statement

A stable white dwarf star has mass m = 10^30 kg and radius R = 8 ×10^8 m. What is the degeneracy pressure of the electron gas in the star?

Relevant Equations

P = 2πc/3h^3 × P(F)^4 × [1 - {mc/P(F)}^2]
where P(F) = h(3N/8πV)^(1/3)

So far, I am provided with all the required values for calculation, except N.
If N = total number of electrons in star, then using N = mass of star/ mass of an electron should be no problem.
Am I right?

 

[SammyS]

Homework Statement:: A stable white dwarf star has mass m = 10^30 kg and radius R = 8 ×10^8 m. What is the degeneracy pressure of the electron gas in the star?
Relevant Equations:: P = 2πc/3h^3 × P(F)^4 × [1 - {mc/P(F)}^2]
where P(F) = h(3N/8πV)^(1/3)

So far, I am provided with all the required values for calculation, except N.
If N = total number of electrons in star, then using N = mass of star/ mass of an electron should be no problem.
Am I right?

That can't be right.

That would work if the white dwarf star were composed entirely of electrons.

 

[tanaygupta2000]

That can't be right.

That would work if the white dwarf star were composed entirely of electrons.

I think N is given by: N = M/(2×Mass of a proton)

 

[SammyS]

I think N is given by: N = M/(2×Mass of a proton)

That may make sense.

What is the typical composition of a white dwarf star?

 

[tanaygupta2000]

Sir usually WDSs are mainly composed of C-12 & O-16.
But the question here is asking about electron gas.

 

[SammyS]

Sir usually WDSs are mainly composed of C-12 & O-16.
But the question here is asking about electron gas.

Right. Each of those atoms has 1 electron for every two nucleons (one proton & one neutron). So, yes you were essentially right when you wrote: N = M/(2×Mass of a proton) .