[mesa-users] Learning stellar evolution and asteroseismology using MESA

[Josiah Schwab]

Hi Cyrus,

> 1) the first step, from what I understand, is to build a pre main sequence.
> I just copy the star/work directory in a personal one, and in the
> corresponding inlist file, we just need to indicate the initial mass and Z
> (0.71 and 0.0001 respectively for my first case). If nothing is wrong up to
> now, my only question would be : what should be stopping condition ? The
> tutorial inlist file indicates Lnuc / L > 0.99 and the astero example
> inlist file indicates a max model number of 30 (by the way, where the first
> one comes "theoretically" ; and for the second one why 30 ?).

Physically, a star reaches the main sequence when L ~ L_nuc.  So the
stopping condition Lnuc / L > 0.99 means that MESA stops when the star
has reached the zero age main sequence (ZAMS).

In the second case, the inlist begins with a pre-main sequence model and
evolves it for a small number of steps.  Why exactly 30 was chosen, I
don't know, but that is significantly less than the number of steps it
will take to reach the ZAMS.  So this model is still a pre-main sequence
(PMS) model, fully convective with a luminosity greater than it will
have on the main sequence.

> 2) Now that I have a pre_ms star can there be one inlist file describing
> the evolution of the star from main sequence to a RR Lyrae type star ? If
> yes, what should be the stopping condition (if I'm not wrong there's no
> predefined stopping condition for that specific purpose...then how would I
> recognize that it has reach a RR Lyrae type model) ? If I'm asking this
> question is that the astero_example inlist file contains not two but three
> inlist, on fro pre MS and two others.

I don't know much about RR Lyraes, but MESA allows you to check any
conditions you want using run_star_extras.f.  See e.g.,

http://mesa.sourceforge.net/run_star_extras.html#toc-2

So first you should write down what physical conditions you want to use
as the stopping trigger.  Then work on translating that into some
fortran code.  You can likely get help with this second step on-list.

In terms of what you should include in your PMS -> RR Lyrae inlists, you
may want to look at some test suite problems or talk with someone
working on this or related topics.

Hope that helps,
Josiah