[Mesa-users] Relaxing Giant Star

[Bradley Munson]

Hello All,

I am using MESA version 21.12.1 on macOS 11.2.2.

I am attempting to use the MESA relaxation procedures to relax a giant star starting from ZAMS. I am relaxing the composition, angular momentum, and entropy (from density and temperature) from the input files I've included here. I've also included the inlist I have been working with.

The outcome is usually either the model crashes during the entropy relaxation process, or it relaxes to a structure that is very different from the input model. The input model comes from a 3D merger model that is spherically averaged, so I understand it will not be in HSE and the EoS is different, but the density and temperature of the MESA model is around an order of magnitude lower than the input model throughout the whole profile (and much lower in the outer 10% of the star by mass). I've attached a couple of plots showing the differences between the input model (dashed line) and MESA relaxed model (blue solid line).

[cid:65ef2bd3-2419-469e-be6c-6c48de18630c]

We've tried turning on and off the gold standards during relaxation, changing the relaxation timescales and max dts, changing the EoS options, starting from pre-MS, changing the energy equation option, and interpolating the input data to get more data points, but nothing seems to help. Has anybody had success with relaxing massive stars in MESA from another code? Does anybody have any advice on what else we can try?

Any help will be much appreciated!

Brad
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