[Mesa-users] Problems with mass_semiconv_core

[Josiah Schwab]

Hi Isaac,

> I was wondering if anyone had experience with the parameter for
> "mass_semiconv_core". I'm running Neptune-mass exoplanets, and during
> an evolution inlist the mass of the core drops from some significant
> value (approximately 5e-5) to 0. There's a corresponding drop in the
> radius of the planet, which seems so abrupt that I don't think it
> could be physical.  I'd appreciate any advice on how to slowly
> decrease the convective core mass, so as to make the radius change
> more gradual, or if this is suggestive of a different problem that I'm
> not thinking of.
>
> The only unique processes going on are irradiation from the standard
> set_column_depth routine, and chemical abundance changes corresponding to
> helium/hydrogen loss that I've specified.

This message doesn't give us much room to help you.

1) Informative plots are much preferred to screenshots of data columns.
(For example, I don't know what "Rad" is and I can't tell whether
something is physically abrupt or not without some sense of time.)

Do you have plots of the way in which the various grads (gradad, gradL,
etc.) are evolving?  Are there weird features or sudden switches?

At the very least, show us what you're looking at to make your
conclusion that something is acting weird.

2) The best way to get someone to take a look at your model is to
specify the version of MESA that you're using and to attach a full work
directory where one can easily exactly reproduce what you're seeing.

Josiah