[Mesa-users] Opacity tables for new and different mixtures.

[Aaron Dotter]

Hi Marc,

The MESA formatted versions of these tables live in mesa/data/kap_data/
after MESA is installed.  The original tables live in
mesa/kap/kap_data.tar.xz and there is a whole suite of codes and scripts
for converting from original to MESA format in mesa/kap/preprocessor/.

I think a great way to make new tables accessible to the community would be
through the MESA Zenodo (https://zenodo.org/communities/mesa/) though there
may be other options as well.

Aaron

On Thu, Sep 15, 2022 at 1:46 PM Marc Pinsonneault <mhpinsonneault at gmail.com>
wrote:

> Thanks much.  Is there a location for the tables (as we can also supply
> some new ones), and a listing of the current recognized mixtures /
> prefixes? If we already have alpha-enhanced for A09 and GS98, I will focus
> on parallel ones for the new mixtures (but having those tables for
> comparison will be quite useful).
>
> cheers
>
> Marc
>
> On Thu, Sep 15, 2022 at 12:13 PM Aaron Dotter <aaron.dotter at gmail.com>
> wrote:
>
>> Hi Marc,
>>
>> Good points all around.
>>
>> There is a set of low- and high-T opacities based on GS98 for [a/Fe]=-0.2
>> to +0.8 in steps of 0.2 dex that already ship with MESA.  These are based
>> on OPAL + Ferguson et al. opacity tables and are originally from my
>> Thesis.  Beyond that, I believe that on Jason Ferguson's webpage there is a
>> set of alpha-enhanced low-T opacity tables for the Asplund 2009 mixture.
>> Not aware of anything like that for the most recent / higher-Z solar
>> abundances.
>>
>> I am also aware of a couple of python scripts that automate, to some
>> extent, the process of generating opacity tables using online forms.
>>
>> Cheers,
>> Aaron
>>
>> On Thu, Sep 15, 2022 at 11:27 AM Marc Pinsonneault via Mesa-users <
>> mesa-users at lists.mesastar.org> wrote:
>>
>>> Hello all.  I’d like to talk about opacity tables.
>>>
>>> Large stellar surveys have really transformed our ideas about how
>>> abundance patterns change in stars;
>>>
>>> there has also been interesting new work on the base solar mixture.
>>>
>>>
>>>
>>> In the former case, at minimum we now know that abundances in stars are
>>> (at least) a 2-dimensional family, usually given as [Fe/H] and {alpha/Fe].
>>>
>>> For example, see Weinberg et al. 2022,
>>>
>>>
>>>
>>> https://ui.adsabs.harvard.edu/abs/2022ApJS..260...32W/abstract
>>>
>>>
>>>
>>> The default mesa cases assume solar [alpha/Fe], and include two “older”
>>> solar mixtures – Asplund 2009 and Grevesse+Sauval 1998.
>>>
>>> There are two recently published solar mixtures.  The “low metallicity”
>>> solution, which builds on Asplund 2021, is Amarsi et al. 2021
>>>
>>>
>>>
>>> https://ui.adsabs.harvard.edu/abs/2021A%26A...656A.113A/abstract
>>>
>>>
>>>
>>> The “high metallicity” solution, also 3D NLTE, is Magg et al. 2022,
>>>
>>>
>>>
>>> https://www.aanda.org/articles/aa/pdf/2022/05/aa42971-21.pdf
>>>
>>>
>>>
>>> Note that the latter is fully consistent with helioseismology, and in my
>>> view it should be the default recommended base mixture.
>>>
>>>
>>> For full self-consistency, one should use high temperature opacities,
>>> low temperature (molecular) opacities, and model atmospheres with the
>>> appropriate mixtures.
>>>
>>> There are public websites that can be used to generate custom opacities
>>> – for example, here is the web interface for the opacity project.
>>>
>>> https://opserver.obspm.fr/rmos.shtml
>>>
>>> and here is the one for the Marigo low temperature opacities
>>>
>>> http://stev.oapd.inaf.it/cgi-bin/aesopus
>>>
>>> However, in practice these do not immediately make tables in formats
>>> suitable for stellar interiors calculations. The standard interiors opacity
>>> tables for MESA (and other evolution codes) use 126 different x / y/ z
>>> combinations, for example, and online resources are one at a time. This
>>> makes quick calculation of new tables challenging.
>>>
>>> Given this, I’m reaching out to the atomic physicists to see if we can
>>> get a more general set of opacity tables for community usage, and this
>>> would include updating the MESA documentation to indicate a more general
>>> set of options / resources. One place where I am stymied, however, and the
>>> reason for this email, is whether this is “already done” in part – e.g. are
>>> there already general tables available for, say, alpha to iron enhancement
>>> that we could point to? Or is this something that we need to make available
>>> as a community resource?
>>>
>>>
>>>
>>> Cheers
>>>
>>>
>>>
>>> Marc Pinsonneault
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> mesa-users at lists.mesastar.org
>>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>>
>>>
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