[Mesa-users] hot accretion and spiky luminosity

[Steindl, Thomas]

Hello all,

I am trying to calculate models of accreting protostars with accretion rates up to 1d-4 M_sun/yr and hot accretion, where the energy is put into the outer layers of star only (typically outer 10% of the radius).  I have tested different methods to put in the extra heat but I decided to use the method which is available on the marketplace (http://cococubed.asu.edu/mesa_market/inlists.html, Michael Kuffmeier) for this thread. In essence, a lot of material is accreted onto the star which leads to extra heat in the surface area.
However, I am having the problem that in the zones below the injection of the extra heat, the luminosity becomes very spiky and the solver is having trouble with convergence. This spikes appear rather random to me and change size and form with almost every timestep. I attach a work directory (latest MESA version) to this mail in order for you to reproduce the problem. This includes pgstar inlist that will show the luminosity profile. The calculations are rather lengthy, therefore i include a model after 400 steps, for you to see the problem immediately if you want. I do not include the star executable as this has ~50mb.
In this case, the extra_heat is put in at a constant level, leading to a jump in extra heat. I have experimented with multiple other ways to put in the extra heat (e.g. in a tanh shape to not have any jumps) but the problem persists.

Do any of you have any idea concerning what causes this spikes and how I can help MESA with the convergence?
As always, I am happy for any input. Thank you very much in advance!

Thomas

__________________________________________________________________
Thomas Steindl, MSc
University of Innsbruck | Institute for Astro- and Particle Physics
Tel: +43 512507 52031
Mail: thomas.steindl at uibk.ac.at
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