[Mesa-users] Differences between MESA versions

[James Wild]

Hi Josiah,

Thanks for the advice, and the offer. I've attached the inlists, and
there's a run_binary_extras.f file that handles residual magnetic braking.

Cheers,
James

On Fri, 26 Feb 2021 at 03:25, Josiah Schwab <jwschwab at ucsc.edu> wrote:

> Hi James,
>
> Is it prudent to trust newer versions of the code over older ones, in this
>> case?
>>
>
> This is a difficult question to answer.  We certainly strive to improve
> MESA with time, so I tend to favor more recent versions, but one can't make
> a blanket statement that models from newer MESA versions are more
> trustworthy.
>
> Ultimately, confidence in the models gets built by:
>
>    Understanding the option choices (including both options you explicitly
> set and key defaults) and their importance in the evolution of the model.
>    Confirming that the models are converged (i.e., checking that the
> results do not significantly depend on the time and spatial resolution)
>    Comparing to other solutions (analytics, previous papers, different
> codes, etc.)
>
> Kudos to you for hitting that last point by doing careful comparisons to
> past work.  The first point can be extra tricky when doing cross-version
> comparisons.  Defaults change, internals are revised, etc.
>
> Without seeing inlists or looking at internal structures, I'd say the
> differences between r8845 and r15140 look like they're at the level where
> they might plausibly be explained by differences in input physics (mostly
> eos & kap) between those versions, though I am not confident in that
> explanation.
>
> As you note, the r12115 results look wrong.  My guess is that there's
> something weird in the inlists.  Feel free to send them along and I can
> take a quick look and see if anything jumps out.
>
> Josiah
>
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