[mesa-users] Appearance of a Helium Core

Michael Medford michaelmedford at gmail.com
Tue Jan 6 17:23:26 EST 2015


Hello,

My time with mesa has been spent investigating the various values for a
star's core boundary depending on which definition one uses. I am evolving
stars of a large range (10 to 80 solar masses) and therefore am looking for
indicators of when the star has reached Terminal Main Sequence that can be
uniformly applied across this wide range.

This is where I discovered a development in the data that I don't
understand how to physically explain. I started looking into the
he_core_mass, figuring that it would gradually grow as the star passed
through the end of the main sequence and entered the subgiant branch.
Instead in all of my stars I have found a sudden increase from an
he_core_mass of 0 to some large value. In the attached example, a star of
60 solar masses experiences a sudden increase from having a helium core of
0 to ~22 solar masses (the x-axis is the model number).

Conveniently this moment occurs when the star is passing through TMS on an
HR diagram, and so I think that I am on the right track. But I am spectacle
of using the variable he_core_mass as my uniform indicator because of it's
unphysical behavior. How does mesa write this variable? And how is it that
the mass of helium does not smoothly grow to this point but instead has
this discontinuity?

I have attached the inlists from several stars, all of which exhibit this
behavior. The histories themselves were too large to attach, but can be
found here:
https://www.dropbox.com/sh/u9ehohb6jl9pi50/AAC_pp0BQvyXdnjHqZ21lpVPa?dl=0

Thank you for any help you can provide.

All the best,
~Michael Medford

-- 
Michael S. Medford
Northwestern University
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