[mesa-users] Eddington Limit

[Kenny Van]

Hey,

Wow thanks, those summer school pdfs are very helpful. They go over most of
what I'm trying to look at.

Thanks



On Mon, Dec 7, 2015 at 1:16 PM, Josiah Schwab <jwschwab at berkeley.edu> wrote:

> Hi Kenny,
>
> > I was going through the code to try and set a different maximum mdot_edd
> > and I noticed inside of binary_mdot.f90 that mdot_edd seems to be defined
> > oddly
> >
> > if (.not. b% use_es_opacity_for_mdot_edd) then
> >             mdot_edd = 4*pi*b% s1% cgrav(1)*b% m(b% a_i)/(clight*b% s1%
> > opacity(1))
> >          else
> >             mdot_edd = 4*pi*b% s1% cgrav(1)*b% m(b%
> a_i)/(clight*0.2*(1+b%
> > s1% surface_h1))
> >
> > Which seem to correspond to:
> >
> > Mdot = 4 pi G M / (c K)
> >
> > and
> >
> > Mdot = 4 pi G M / (c (1 + X))
> >
> > Is this equivalent to the normal representation of
> >
> > Mdot = 4 pi c R / K?
> >
> > While the units appear to match, I would assume that the two are not
> > necessarily equivalent. Unless I'm misunderstanding the code here. Does
> > anyone have some insight to this?
>
> Well, it is equivalent if you set R = GM/c^2. :)
>
> There's not a universally useful definition of Mdot_edd, given that MESA
> can evolve both point mass and non-point mass companions.
>
> Users should make use of the other_mdot_edd hook and define the Mdot_edd
> that is appropriate for your problem.
>
> You may be interested to look at Sterl Phinney's labs from the most
> recent MESA summer school.
>
>
> http://mesastar.org/teaching-materials/2015-mesa-summer-school/phinney-lecture-2-advanced-mass-transfer-and-binary-extras
>
> Josiah
>
>
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