[Mesa-users] Standard Solar Model initialization

[Noah Tuchow]

Thanks for the quick reply.

I suppose that rather than recreating this model file exactly, using the
2010 version of MESA, I would like to try and use the current version of
MESA to create a very similar model which incorporates the same physics. To
do this, I am interested to know how exactly the length of the first 370
timesteps was specified, and which modern inlist arguments would be
analogous to those used back in 2010.

When I referred to MESA crashing, I realize that I was referring to an
earlier version of my inlist where in the first few steps it would reach
the max number of retries and quit. Now if I run MESA while setting
load_saved_model= .false., it struggles on the first steps giving me
multiple messages that the first model is slow to converge after 250 tries,
and that the hydro_newton_step failed to accept. It will still run until I
tell it to stop at the current age, but the output will be a bit off. It
makes sense why one would use a separate inlist for the first few steps to
avoid these errors and save a model file. I would like to know how I can
best replicate the type of pre-main sequence contraction that was used to
make the earlier model file in order to make my own model files starting
from slightly different initial conditions. For instance, if I wanted to
consider the sun as having an initial mass of 1.01 solar masses and losing
0.01 msun from some custom mass loss mechanism, I imagine I would have to
use a different model file than the solar_calibration_input.mod.  How would
you recommend that I model the first few timesteps of pre-main sequence
contraction in a way consistent to the methods used to create the
solar_calibration_input.mod model file?

Thanks for your assistance,
Noah Tuchow

Noah TuchowPenn State UniversityDepartment of Astronomy and Astrophysics532C
Davey LabUniversity Park, PA 16802


On Tue, Oct 9, 2018 at 8:38 AM Aaron Dotter <aaron.dotter at gmail.com> wrote:

> Hi Noah,
>
>
>
>  but find that both my model and the test_suite example don't appear to be
>> initialized from the premain sequence and instead load a model from the
>> file 'solar_calibration_input.mod'. I'd like to know how exactly this model
>> file was made and with what inlist
>>
>
> solar_calibration_input.mod was made using a previous version of the
> inlist used in the solar calibration test suite case you're running.  Also
> a previous version of MESA and (likely pre-MESA SDK) compiler.  If you look
> at the contents of the file, you'll see the creation date is 20100823 so
> it's 8 years old.
>
> I'm a bit confused as to what exactly the model I'm loading is, because
>> some of the arguments used in the solar calibration inlist in the example
>> appear to be for initializing a premain sequence model with from a cloud
>> with uniform composition, specified mass fractions and abundances.
>>
>
> The purpose of using such a model is to skip over the first 370 timesteps
> (model number is 371) of pre-main sequence contraction and the construction
> of the pre-main sequence structure.  This saves a fair amount of time
> without causing egregious errors in the results.
>
>
>> I've noticed that MESA crashes if I keep all the inlist arguments the
>> same values and just start with set_uniform_initial_composition = .true.
>> without loading the model, and I think that this is likely due to
>> having which_atm_option = 'photosphere_tables'.
>>
>
> What do you mean by "MESA crashes"?  What does the terminal output say?
> If you try to run the solar calibration inlist without loading a model AND
> without setting create_pre_main_sequence_model = .true., MESA will try to
> load a ZAMS model but it's unlikely to have one with your specific
> composition.  It's unlikely that this has anything to do with
> photosphere_tables for the atm.
>
>
>
>> Since this example doesn't appear to have any documentation, I'm curious
>> to know how this model file was made and what I should do to initialize a
>> model for a slightly different sun.  Does anyone have the inlists used to
>> make the model file?
>>
>
> See my first response above.  It's possible that the model could be
> recreated with MESA circa mid-2010 but I don't think it's worth the
> trouble.
>
> Aaron
>
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