I am trying to calculate at which point gravitational equilibrium sets in for various bodys (planets stars neutron stars etc.) assuming they are perfect spheres. However the radius i get is not equal to what it should be according to wikipedia (i tried for the sun a planet and a neutron star, all of them were off by quite a bit)
below is the example of the neutron star radius i m trying to get
my result (factor) is 1 at:
Radius : 2228588 m
Density: 1.2768744892680034E11 kg / m^3
the wikipedia article about neutron stars says radius of a neutron star is about 12 km and the density about 10 times higher than mine but my result is 2228km which is quite a bit off, so i got a 2 part question:
a) am i calculating all forces i need?
and
b) are the formulas i am using correct?
i took them from wikipedia and / or university slides and i found multiple variations of almost all of them(most of which i actually didnt list below), so i m quite confused as to what is correct
i know that i m using iron as element and i should split it up and convert the protons to neutrons but that would only increase the degegeneracy pressure further resulting in an even bigger radius if i m not mistaken.
heres how i calculated it (everything behind a "!" is a comment that describes what it is):
!radiantion constant in Wm^-2K-4
$sbolzmann = 5.67036713E-8$
!radiantion constant in J / K
$kbolzmann = 1.3806485279E-23$
!gravity constant
$GRAVITY = 6.67408E-11$
! 1 mol
$mol = 6.02214085774E23$
! 1 u (atomic mass )in kg
$ u = 1.66053904020E-27$
! mass of 1 electron in kg
$ me = 9.1093835611E-31$
!hydrogen mass
$ mh = 1.00782503223 * u $
!neutron mass
$ mn = 1.00866491585 * u$
! speed of light, in m / s
$ c = 299792458 $
! plank constant h in kg * m^2 / s
$ hp = 6.62607004081E-34$
! reduced plank constant hr in kg * m^2 / s
$ hpr = frac{hp }{ (PI * 2)}$
$ amount = 79378857878009573048911997815206 $
! iron with 26 protons 30 neutrons
$ element = 26Fe56$
$ elementmass = 55.934936$
$ atoms = amount$
$ neutrons = (56-26) * amount$
$ electrons = 26 * amount$
$ particlecount = atoms + electrons$
!4.4400513610370694E30 kg, about 2.3 Mass of the sun
$Mass = elementmass * amount $
$Radius = 2228588$
$Temperature = 9.45179584120983E-7$
$ fgravitation = frac{GRAVITY * (Mass^2)} { Radius }$
$volume = ((frac{4.0}{ 3.0}) * PI * (Radius^3))$
!density in particles / m^3
$ particledensity = frac{ particlecount }{ volume}$
$a = 4.0 * frac{sbolzmann}{c}$
!radiation pressure in J / m^3
$ rpressure = frac{1.0 }{ 3.0} * a * (Temperature^4)$
!gas pressure in J / m^3
$ gpressure = particledensity * kbolzmann * Temperature$
!electron degeneracy pressure
$ epressure = (frac{(PI^3) * (hpr^2)} { (15 * me)}) * ((frac{3 * electrons} { (volume * PI)})^(frac{5.0 }{ 3.0}))$
! electron degeneracy pressure formula 2
$ epressure2 = frac{((PI^2) * (hpr^2))} { (5 * me * (mh^ (frac{5.0 }{ 3.0})))} * ((frac{3.0 }{ PI})^ (frac{2.0 }{ 3.0})) * (( frac{(frac{Mass }{ volume})}{ 1})^ (frac{5.0}{ 3.0}))$
!neutron degeneracy pressure
$ npressure = frac{(PI^3) * (hpr^2) }{ (15 * me))} * ((frac{3 * neutrons} {(volume * PI)})^(5.0 / 3.0))$
!neutron degeneracy pressure formula 2
$npressure2 = frac{((3^(frac{10.0}{3.0})) * (hpr^ 2)) }{ (15 * (PI^(frac{1.0} { 3.0})) * (mn^ (frac{8.0} { 3.0})) * (radius^ 5))} * ((frac{Mass} { 4})^(frac{5.0} { 3.0}))$
$totalpressure = gpressure + rpressure + npressure + epressure$
$totalpressureforce = totalpressure * volume$
!if factor = 1 then the body is in equilibrium
$ factor = frac{totalpressureforce }{ fgravitation}$
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