[mesa-users] PMS evolution and cold/warm accretion

[Troels Haugbølle]

Dear Bill,

Thanks for the fast response, I will try to experiment a bit with the hook myself, if there are not any other suggestions.

best,

Troels

On 03 Jun 2014, at 19:27 , Bill Paxton <paxton at kitp.ucsb.edu<mailto:paxton at kitp.ucsb.edu>> wrote:

On Jun 3, 2014, at 7:03 AM, Troels Haugbølle wrote:

Dear MESA developers,

I have just started using MESA to explore pre-main-sequence and protostellar evolution with variable accretion.

I have been looking into the code, and set up a hook for loading tabulated accretion rates, and I think I have also enabled deuterium burning, and got the right opacity tables, but I was wondering if there is a way to control the entropy of the accreeting material.

In particular, if material is added to the star through accretion channels from e.g. a disk, one get “cold accretion”, with the entropy of the new material being the same as in the disk, while if it is accreting enclosed in an envelope it can be hot accretion.

Is it possible to control this in MESA ? And if not, where should I look to do it

best regards,

Troels Haugbølle


There is no built-in mechanism for setting entropy of accreted material.  Perhaps you can model it by an extra power source in a surface layer by using the "other_energy" hook.  If you try that, be sure to spread the added energy over a set of cells -- if you try to put it all into the outermost cell, you probably will have convergence problems.  perhaps try spreading it over the surface cells that contain roughly the amount of mass added per timestep.

I believe there are users who have experience doing this sort of thing.  They might have other suggestions.

Cheers,
Bill

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