[Mesa-users] changing physical constants in MESA

[Josiah Schwab]

Hi Lillian,

I would like to run the MESA code with altered values for constants such as
> the fine structure constant, proton mass, and electron mass. I initially
> attempted to do this by setting some of the variables from the file $MESA_DIR/const/public/const_def.f90
> to different values in the subroutine *extras_controls* in the file $MESA_DIR/star/work/src/run_star_extras.f
> (after copying and pasting the contents of standard_run_star_extras.inc).
> This worked for some constants, but when I tried different values for the
> fine structure constant, there was no change in the output. Is this because
> the fine structure constant is automatically built into the cross section
> calculations? If that is the case, is there any way to change the fine
> structure constant within the code? Also, I encountered the same issue with
> the proton mass.
>

You cannot alter those constants in MESA in any meaningful way.  For
example, key microphysics data (opacities, equation of state, etc.) assumes
the measured values of these quantities.

Josiah
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20210331/3dc2e8ef/attachment.htm>