Re: [mesa-users] How to set metallicity for a binary system

[Pablo M. <pa...@gm...>]

Erick, to use the initial_z option you need to either:

- Start from a pre-main sequence model by using:
     create_pre_main_sequence_model = .true.
in your star_job options. This wont work very well when modelling binaries,
as a pre-main sequence star is very large and will likely begin evolution
with an enormous amount of overflow. You can bypass this however with the
option
     ignore_rlof = .true.
in binary_controls, which will cause Roche lobe overflow to be ignored. If
you do this, you need to set ignore_rlof = .false. once the star reaches
the ZAMS, either manually by stopping the run, changing the option in the
inlist file, and restarting the run, or automatically, by implementing
these options in run_binary_extras.f

- Create your own ZAMS models for the specific metallicity you want. To do
this, you can follow the test_suite case star/test_suite/create_zams, and
modify the inlists accordingly (the options you want to change are in
inlist_zams_specification). This will create a file with ZAMS models, which
you can then copy to "$MESA_DIR/data/star_data/zams_models/". Once you do
that, you can tell MESA to use this models by including
     initial_z = 1d-2
     zams_filename = 'my_ZAMS_models.data'
in the "controls" section of your inlist (here I assumed you named your
file with ZAMS models 'my_ZAMS_models.data').

- Relax the composition of the star to what you want. This means that I
start from the MESA ZAMS models with metallicity 1d-2, and adjust the
composition until it reaches the values I require. I normally do this by
including these options:
    set_uniform_initial_composition = .true.
    initial_h1 = 0.70d0
    initial_h2 = 0d0
    initial_he3 = 0d0
    initial_he4 = 0.28d0

    relax_initial_Z = .true.
    new_Z = 0.01
    relax_initial_Y = .true.
    new_Y = 0.26d0
Into "star_job". Note that you should specify both Z and Y here (and for
the previous two options you should also check this!). This however does
not quite result in a ZAMS model, but its close to being one.

>From these three options, I'd recommend you go for number 2. If you're
still missing something, let me know.

Cheers!

On Tue, Mar 1, 2016 at 2:48 AM, Ruiz, Erick <eri...@tt...> wrote:

> Dear Robert,
>
>
> Thank you for your help. I tried that after I posted my question, but I
> got the following error message:
>
>
> WARNING: requested initial_z does not match zams file initial_z.
>                                     zams file initial_z
>  2.0000000000000000D-02
>                                     requested initial_z
>  1.0000000000000000D-02
>
>
>
>  failed in get_zams_model
>  star_load_zams ierr          -1
>  do_load1_star ierr          -1
> DATE: 2016-02-29
> TIME: 11:02:16
>
> Am I supposed to update initial_z elsewhere?
>
>
> Best regards,
>
>
> Erick Ruiz
>
>
> ------------------------------
> *From:* Robert Farmer <rjf...@as...>
> *Sent:* Monday, February 29, 2016 11:12 AM
> *To:* Ruiz, Erick
> *Cc:* mes...@li...
> *Subject:* Re: [mesa-users] How to set metallicity for a binary system
>
> Hi
> So the inlist_project in the binary work folder is for setting the binary
> parameters. There is also the inlist1 and inlist2 files in the binary work
> folder, these are what sets each stars parameters.
>
> Rob
>
> On Mon, Feb 29, 2016 at 9:55 AM, Ruiz, Erick <eri...@tt...> wrote:
>
>> Hi,
>>
>>
>> I know how to set the initial metallicity when evolving a single star
>> (change initial_z in the inlist_project). However, I would like to evolve a
>> binary for several metallicities. I tried to do the same thing as for
>> single stars; I set the metallicity in the inlist_project as follows:
>>
>>
>> initial_z = 0.02d0
>>
>>
>>
>> However, I got the following error message:
>>
>>
>>
>> Failed while trying to read binary control namelist file: inlist_project
>> Perhaps the following runtime error message will help you find the
>> problem.
>>
>> At line 229 of file ../private/binary_ctrls_io.f (unit = 29, file =
>> 'inlist_project')
>> Fortran runtime error: Cannot match namelist object name initial_z
>> DATE: 2016-02-29
>> TIME: 10:04:52
>>
>>
>>
>> I looked at binary_ctrls_io.f and noticed that initial_z is not included,
>> unlike other parameters such as initial_period_in_days. Does this mean that
>> it is not possible to change the initial metallicity of a binary? If it is
>> possible, how is it done?
>>
>>
>> Best regards,
>>
>>
>> Erick Ruiz
>>
>>
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-- 
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD student, Argelander-Institut für Astronomie