[mesa-users] A common stellar-structure myth

[Francis Timmes]

agreed. in fancier treatments of the homology (thank you john faulkner!)
the opacity can be isolated, L ~ M^alpha / kappa. for a kramer, 
kappa ~ rho T^(-7/2), leading to L ~ M^(5.5) / R^(0.5).

a fascinating thread methinks :)

fxt



> On Aug 30, 2016, at 5:36 PM, Craig Wheeler <wheel at astro.as.utexas.edu> wrote:
> 
> Alex's stars probably are dominated by electron scattering,
> at solar the opacity may be more Kramers...
> 
> Craig
> 
> 
> On 8/30/16 7:20 PM, RICHARD H D TOWNSEND wrote:
>> Hi Alexander —
>> 
>> Interesting! I wonder whether this is a result of degeneracy behaving differently in the Pop I vs Pop III cases. What initial metallicity did you assume — zero, or something small?
>> 
>> cheers,
>> 
>> Rich
>> 
>>> On Aug 30, 2016, at 7:12 PM, Alexander Heger <alexander.heger at monash.edu> wrote:
>>> 
>>> Dear Richard,
>>> 
>>> I just looked at two stars, admittedly Pop III stars, and those, middle of H burn, pressure is 10x higher in 10 M_sun star compare to the 1 M_sun star.  Both half way through H burn.
>>> 
>>> Maybe an interesting difference to Pop I.  And related to the shape of the curve in Ibeling & Duligur (2013).
>>> 
>>> Never mind, gravitational acceleration is zero in the centre of both stars.
>>> 
>>> -Alexander
>>> 
>>> On 31 August 2016 at 09:56, RICHARD H D TOWNSEND <townsend at astro.wisc.edu> wrote:
>>> Hi Alex —
>>> 
>>> In the context of an entry-level astronomy textbook, I think ‘gravity’ is intended to reference acceleration (which students have every-day experience of) rather than potential (which they don’t).
>>> 
>>> Regarding pressures — as you can see from the plot below, the pressure at the center of the massive star is about 0.5 dex smaller than that at the center of the solar-mass star. So, comparing pressures doesn’t help here.
>>> 
>>> Rich