[Mesa-users] Use of OPAL table with specific chemical composition

[Farag, Ebraheem]

Hello,

The OPAL opacity tables are run through preprocessing routines which spline and smooth them. If your OPAL tables are not already splined, you'll need to look into the $MESA_DIR/kap/preprocessor scripts and determine how to run them on your opacities.

If your tables have already been run through the smoothing spline routines, or if you just want to use the raw tables, just paste them directly into $MESA_DIR/data/kap_data/.

On using custom user tables:

If you are generating the standard 126 opal tables in an identical format and grid size. Something like the following should work in your kap inlist:

      kap_file_prefix = 'Custom_OPAL_tables' # example prefix for your tables

      user_num_kap_Xs = 10
      user_kap_Xs =0.0d0,0.1d0,0.2d0,0.35d0,0.5d0,0.7d0,0.8d0,0.9d0,0.95d0,1.0d0

      user_num_kap_Zs = 13
      user_kap_Zs =  0.0d0, 0.0001d0, 0.0003d0, 0.001d0, 0.002d0, 0.004d0, 0.01d0, 0.02d0, 0.03d0, 0.04d0, 0.06d0, 0.08d0, 0.1d0

      user_num_kap_Xs_for_this_Z = 10,10,10,10,10,10,10,10,10,10,9,9,8

# Note, you might want to double check these by following the instructions here https://docs.mesastar.org/en/latest/kap/defaults.html#custom-tables for more details.

It is additionally recommended that one test their opacity tables, by using the $MESA_DIR/kap/plotter functionality, before incorporating them into a stellar model.

-EbF

________________________________
From: Mesa-users <mesa-users-bounces at lists.mesastar.org> on behalf of mutlu yildiz via Mesa-users <mesa-users at lists.mesastar.org>
Sent: Monday, July 14, 2025 3:22 AM
To: mesa-users <mesa-users at lists.mesastar.org>
Subject: [Mesa-users] Use of OPAL table with specific chemical composition

Dear MESA Users,

I want to use the opacity table I calculated for a specific chemical composition on the OPAL website instead of the opacity options available in MESA.
Thank you in advance for your help on this matter.

Cheers,
Mutlu

--
Ege Üniversitesi Fen Fakültesi
Astronomi UBB 35100 Bornova İzmir
https://orcid.org/0000-0002-7772-7641
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