[mesa-users] Hook in HR when hitting max_age

[Radek Smolec]

Hi Aaron,

>
> The a09p in the low-temperature opacities is the standard Asplund et al.
> 2009 mixture based on photospheric abundances (as opposed to meteoritic).
>  Here 'p' refers to photosphere, not Przybilla.  The reason for making a
> choice in the low-T tables is that the low-T opacities include all the
> elements H through U (or more?) whereas OPAL only 20 elements or so.  Some
> of the elements cannot be measured in the solar spectrum; some can be
> measured in the spectrum AND meteorites but the respective values differ
> (esp. Li).  So one has to choose.  Since Li is irrelevant to OPAL, it makes
> no difference.  It is unfortunate that there is some ambiguity in the names.
>
Thanks a lot for clarifying. I think I assumed that this 'p' indicates
Przybilla after looking at initial_zfracs in chem_def.f. Also lack of 'p'
in other mixtures is somewhat confusing (they are always photospheric,
right?)


>
> I have seen the small jump in the final (shorter) timestep in other codes
> but I don't remember seeing it in MESA.  Can you say how long the final
> timestep is?  And what if you increase the max_age somewhat, so that the
> normal evolution goes beyond 4.57 Gyr?
>
The last time step was logt=6.501511470, while previous steps where logt=7
(set by max_years_for_timestep = 1d7 in diffusion settings). I run the
evolution with max_age=4.8d9 - see plot. The tracks are of course identical
till 4.57d9, as max_age was the only modification of inlist. But track with
max_age=4.8d9 smoothly passes around 4.57d9 and ....ends with a hook. So it
seems something goes wrong with the last time step.
Cheers,
Radek
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