[Mesa-users] runaway mass transfer in WD-WD binary

[Kareem El-Badry]

Hello MESA users,

I'm trying to simulate mass transfer from a low-mass He WD (0.13 Msun) onto
a point mass that represents a massive WD (1.1 Msun). Mass transfer should
be stable and the period should increase once mass transfer begins [I
think] because (a) the orbit expands when the He WD loses mass, and (b) the
radius of the He WD increases when it loses mass, reestablishing contact
with the Roche lobe at a longer period.

However, in the MESA calculations, Mdot gets very large as soon as the He
WD overflows its Roche lobe, and the calculation grinds to a halt. I've
attached inlists and a model.

I am using version 12778.

Some things I have tried:
- decreasing varcontrol_target and mesh_delta_coeff
- decreasing fm and fr
- setting set_to_this_tau_factor = 30
- turning off diffusion


But none of these had an appreciable effect. Does anyone have relevant
experience or an idea what the problem might be?

Thanks,
Kareem
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