[mesa-users] Weird jumps in radius for rotating 8.1Msun model

[Aaron Dotter]

Hi Rich,

You're delving into the murky depths of science now!  It has been
appreciated for many years that some amount of convective core overshoot is
required to match the observed CMDs of open clusters.  It is common to
assume an overshoot mixing height of 0.2 H_p for stars more massive than 2
Msun, but this 0.2 H_p is in terms of a fully-mixed region rather than the
exponential mixing that you're using now.  To my knowledge, no one has
"calibrated" the exponential overshoot with open clusters.

Of course, MESA can do overshoot the old way, too:

            ! optional step function for overshooting to be used in place
of exponential
            overshoot_step_fraction = 0 ! use this if > 0

               ! as above, f0*Hp determines r0 where switch from convection
to overshooting.
               ! D0 = diffusion coefficient D at point r0
               ! Hp0 = the scale height at r0.
               ! overshooting extends a distance f*Hp0 from r0
               ! with constant diffusion coef D = overshoot_step_fraction*D0

I'd be happy to continue this conversation with you off-list if you want to
talk about the science side of things.

Aaron
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