[mesa-users] MESA 6749 "noisy" tracks

[Sibilla Perina]

Hi
As a first test I did this.
I noted that the default values of mesh_delta_coeff (1.0) and
varcontrol_target (1e-4) are the same in the mesa versions 4589 and 6794.
However, they produce different space/time resolution (tip1.pdf); why?
Then, I run 6794 with mesh_delta_coeff 1.0, 0.6, 0.5, 0.4, and
varcontrol_target 1e-2, 1e-4.
The result most similar to the 4589 one is obtained with 6794 assuming
mesh_delta_coeff = 0.5 and maintaining varcontrol_target as default
(1e-4)(tip2.pdf).
In addition to the tiny difference in logL (0.02) and logTeff (0.003),
there is an age difference of about 450 thousand years between the two
rgb-tip. Moreover, the 6794 execution-time is tripled.
(tip3.pdf shows 6794 tracks assuming the two different parameter pairs).

Cheers,
Sibilla

2014-10-23 15:06 GMT-03:00 Sibilla Perina <sibilla.perina at gmail.com>:

> Time ago I computed a set of evolutionary tracks using MESA 4589 (SDK
> 20120728). Now I’m computing the same tracks with MESA 6794 (SDK 20140715).
> I’m on OSX 10.8.5.
>
> I’m using the multimass method. The inlist is the same for both the
> versions. The two run_star_extras.f have some differences I think due to
> the code upgrade, but they should do the same things. I attached here the
> two inlist and the two run_star_extras.f.
> In the attached figure tip.pdf I plotted two tracks (M=1.0 Msun, Z=0.02)
> corresponding to the different MESA versions, in a HR region very near to
> the RGB tip.
>
> I’d like to know why the track from the new MESA version is so noisy
> respect to the other and if there is a way (parameter setting) to obtain a
> more cleaned track as the one from the older MESA version. Moreover, why
> there is that difference in the tip location?
>
> Thanks for your help.
> Cheers,
> Sibilla
>
>
>
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