[Mesa-users] Mesastar Question: Setting Initial CO Abudance Enhancements

[KAYLA MARTIN]

Hi Lynn, Evan,

I am wondering if I could get your help with problem solving for the method
you suggested.

As far as I can tell, I am implementing the z_fraction_* settings
correctly. However, when I try to run my model it only just gets past
relax_to_radiative_core before throwing an error(?) about the custom
composition. Based on O_cntr and other similar values printed to the
terminal before the error, the z_fraction_* specifications seem to have
worked... so, I am not sure why the model is not then continuing to evolve
past this point -- I am not even certain if the pre-MS model is created
before the error occurs.

I have attached a text log of the terminal output (incl. the error at the
end), as well as a copy of my inlist. Are you able to take a brief look and
let me know what I may be missing? Any suggestions on how to get past this
point? I am having no luck.

Kind regards,

*Kayla Martin --*
*PhD Candidate (Astronomy & Astrophysics)*
*Administration Assistant, Association for Astronomy*
*Desk 504, 12 Wally’s Walk (Level 5), Macquarie University*


On Fri, Aug 2, 2024 at 12:48 AM Buchele, Lynn <lynn.buchele at h-its.org>
wrote:

> Dear Kayla (sending this again as I forgot to cc the mailing list) ,
> I can give an initial answer to your questions, although others on the
> list may have more details to add. For setting the composition, I'm
> guessing that your composition changes are at the level of elements, not
> isotopes.
> In this case (and assuming you create your model with either
> create_pre_main_sequence_model or create_initial_model), you can set
> set_uniform_initial_composition = .true. and
> initial_zfracs = 0 in star jobs and set the element abundances using
> z_fraction_* in the controls section (
> https://docs.mesastar.org/en/release-r24.03.1/reference/controls.html#accretion-dump-missing-metals-into-heaviest
> this points to a section about accretion but the z_fraction_* controls are
> also used in generating an initial model). For this, you need to set all
> the elements and have them sum to one.
>
> If you want to make changes to the abundance of isotopes (rather than
> elements) you can use set_uniform_initial_xa_from_file, see
> https://docs.mesastar.org/en/release-r24.03.1/reference/star_job.html#set-uniform-initial-xa-from-file.
>
>
> As for custom opacity tables, you are correct that AESOPUS only provides
> low temperature opacity tables. It looks like the webpage for generating
> custom OPAL tables is down, but you might be able to use OP tables which
> you can generate here: http://op-opacity.obspm.fr/opacity/
> The caveat is that these only generate type 1 tables, which won't account
> for changes in the C/O ratio. If you're only dealing with hydrogen burning,
> this shouldn't be a problem. You can look at when MESA (by default) starts
> using type 2 tables here:
> https://docs.mesastar.org/en/release-r24.03.1/kap/defaults.html#use-type2-opacities
> If you do need type 2 tables, perhaps someone else on the mailing list has
> a suggestion for how to generate them.
> I think the preprocessor instructions given in the README should work (you
> can use the inlist_OP_* as a template since your custom files should be in
> the same format). The inlists discussed here are inlists for the opacity
> preprocessor, not the star kap insists, so they will have different options
> available. Otherwise, you can provide information about the structure of
> the tables in the kap inlist using the controls described here:
> https://docs.mesastar.org/en/release-r24.03.1/kap/defaults.html#custom-tables.
>
> For the lowT AESOPUS tables, you only need to use the inlist parameter
> AESOPUS_filename.
>
> Hopefully this helps!
>
>
> Best,
> Lynn
>
> ------------------------------
> *From:* Mesa-users <mesa-users-bounces at lists.mesastar.org> on behalf of
> KAYLA MARTIN via Mesa-users <mesa-users at lists.mesastar.org>
> *Sent:* Thursday, August 1, 2024 9:48:50 AM
> *To:* mesa-users at lists.mesastar.org
> *Subject:* [Mesa-users] Mesastar Question: Setting Initial CO Abudance
> Enhancements
>
>
> This email originates from an external sender. Please verify the sender's
> identity carefully before opening any attachments or links!
>
> Hi,
>
> This is my first post on the mesa user list.
>
> I am creating a model with X=0.732, Y=0.26, and Z=0.008, with the chemical
> composition mixture of Grevesse & Sauval (1998). In this model, I need to
> set [O/Fe]=+0.2 (equivalent to [O/H]=-0.1 or X(O)=0.0042), though I cannot
> see a clear way to implement this in my model.
>
> I have attempted to create an opacity table using the AESOPUS tool
> <http://stev.oapd.inaf.it/cgi-bin/aesopus>, though it seems this only
> applies at 'low temperatures' (the tool won't let me set higher than
> Teff=log3.7)? Further, the implementation of the tables generated from this
> tool are unclear -- the related instructions in mesa have outdated
> information (last updates ~2013), and contains variables that no longer
> exist in more recent mesa versions (e.g.,
> $MESA_DIR/kap/preprocessor/README_creating_OPAL_type2_tables notes inlist
> variables such as Zfrac_O).
>
> Any guidance on how to correctly specify the initial oxygen abundance in
> my model with a gs98 reference solar composition will be very helpful.
>
> Thanks!
>
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