[Mesa-users] New MESA release candidate r24.06.1-rc1

Mon Jun 17 17:38:17 UTC 2024

Hello everyone,

We are pleased to announce a beta public release of MESA, r24.06.1-rc1
<https://docs.mesastar.org/en/release-r24.06.1-rc1/>, which can be
downloaded from Zenodo: https://zenodo.org/records/11502397

As a reminder, we are now making a pre-release version of MESA available
for testing before a full release. We expect the full release around the
start of August. The release candidate should not be used for science, but
we expect it will be close to the final released version. We encourage
users to test the release candidate and send feedback to the developers if
they feel that updates to MESA may impact their science.

For a complete list of important changes since the last release, see the
changelog <https://docs.mesastar.org/en/release-r24.06.1-rc1/changelog.html>.
Here is a brief summary:

New Features:

High Temperature Opacity Tables

Type 1 Rosseland-mean opacity tables from The Los Alamos OPLIB database (Colgan
et al. 2016 <https://ui.adsabs.harvard.edu/abs/2016ApJ...817..116C/abstract>)
are now available (Farag et al. 2024
<https://doi.org/10.3847/1538-4357/ad4355>). These tables cover the region
0.0 ≤ X ≤ 1 − Z and 0.0 ≤ Z ≤ 0.2. Each set of OPLIB opacity tables
contains 1194 individual tables, a dramatic increase in table density (in
the X–Z plane) over the standard 126 individual tables provided in previous
opacity releases. These tables are available for four solar-scaled
abundance mixtures constructed from photospheric estimates of the solar
heavy element abundance: (GS98, Grevesse & Sauval 1998
<https://ui.adsabs.harvard.edu/abs/1998SSRv...85..161G/abstract>),
(AGSS09(a09p),
Asplund et al. 2009
<https://ui.adsabs.harvard.edu/abs/2009ARA%26A..47..481A/abstract>), (AAG21,
Asplund et al. 2021
<https://ui.adsabs.harvard.edu/abs/2021A%26A...653A.141A/abstract>), and (MB22,
Magg et al. 2022 <https://doi.org/10.1051/0004-6361/202142971>). Users can
adopt this new set of tables by selecting one of the following options for
kap_file_prefix:

   -

   'oplib_gs98'
   -

   'oplib_agss09'
   -

   'oplib_aag21'
   -

   'oplib_mb22'

See Overview of kap module
<https://docs.mesastar.org/en/release-r24.06.1-rc1/kap/overview.html#overview-of-kap-module>
and kap_file_prefix
<https://docs.mesastar.org/en/release-r24.06.1-rc1/kap/defaults.html#kap-file-prefix>
for more details on the implementation of these tables. For further details
on these new OPLIB opacity tables, a direct comparison with the Type 1
OPAL/OP tables as well as their effect on solar models can be found in Farag
et al. 2024 <https://doi.org/10.3847/1538-4357/ad4355>.

Low Temperature Opacity Tables

Low temperature Rosseland-mean opacity tables for both (AAG21, Asplund et
al. 2021 <https://ui.adsabs.harvard.edu/abs/2021A%26A...653A.141A/abstract>),
and (MB22, Magg et al. 2022 <https://doi.org/10.1051/0004-6361/202142971>)
solar-scaled abundance mixtures have been privately communicated by Jason
Ferguson. These opacity tables were computed following the approach of Ferguson
et al. (2005)
<https://ui.adsabs.harvard.edu/abs/2005ApJ...623..585F/abstract>. Users can
adopt this new set of tables by selecting one of the following options for
kap_lowT_prefix
<https://docs.mesastar.org/en/release-r24.06.1-rc1/kap/defaults.html#kap-lowt-prefix>
:

   -

   'lowT_fa05_mb22'
   -

   'lowT_fa05_aag21'

Opacity interpolation

We have updated the opacity interpolation scheme to provide much higher
quality derivatives when doing cubic interpolation in composition. MESA
interpolates across opacity tables in the X–Z plane through the use of two
consecutive 1D splines. MESA offers users the ability to choose linear or
cubic interpolation for these splines, while leaving the default as linear
interpolation.

‘cubic_interpolation_in_X = .false.’

‘cubic_interpolation_in_Z = .false.’

This choice of default was primarily due to the fact that the previous
cubic composition interpolation scheme in MESA suffered from poor quality
interpolated opacity derivatives with respect to density and temperature,
which often disagreed with the numerical derivatives produced via nearest
neighbor Richardson extrapolation.

Chem
New initial metal mass fractions initial_zfracs taken from photospheric
estimates of the solar heavy element abundances in (AAG21, Asplund et al.
2021) and (MB22, Magg et al. 2022) are now available. See initial_zfracs
<https://docs.mesastar.org/en/release-r24.06.1-rc1/reference/star_job.html#initial-zfracs>
for more details.

Bug Fixes:

   1.

   There has been a bug present in the rates module due to the incorrect
   phase space factors for reverse reaction rates involving greater than 2
   reactants or products. This bug resulted in inconsistent equilibrium
   compositions when the network evolves into nuclear statistical equilibrium
   (NSE), at temperatures exceeding 4 GK. This bug effects users who evolve
   models into NSE using large reaction networks. This includes evolving
   massive stars to core-collapse. Smaller networks such as the ‘approx21’
   networks are less affected. We strongly recommend that users update to the
   latest MESA release. See gh-575
   <https://github.com/MESAHub/mesa/issues/575>
   2.

   MESA no longer produces a segmentation fault if it tries to increase the
   number of cells beyond max_allowed_nz.
   3.

   A bug in the pgbinary axes definitions resulted in models crashing when
   running in single star mode and has been corrected. Another bug inhibited
   the mass of the not modeled star from being displayed in the pgbinary panel
   and has also been corrected. See gh-634
   <https://github.com/MESAHub/mesa/issues/634>

With thanks to the following members of the community for contributions:
Ryosuke Hirai, Mathieu Renzo, Aldana Grichener

We welcome contributions from the community. If you want to contribute to
MESA, we have a guide:https://docs.mesastar.org/en/latest/contributing.html
<https://urldefense.com/v3/__https://docs.mesastar.org/en/latest/contributing.html__;!!IKRxdwAv5BmarQ!dFfyYL414f_nuyOgsnLUOCwR73pHNQ0WutdCYaJKVaWvAyNBAlVyNV98jydPqr2KuL2IuK6aDwXNeiNT6AE3hWlV$>

Contributions can take many forms, including bug reports, documentation
fixes, and new code or science. Not everyone has to be a coder to
contribute. If you have something you want to contribute but have doubts
about it, then feel free to reach out to any of the MESA developers and we
can provide help and guidance.

Cheers,
Ebraheem, on behalf of the MESA developers
<https://urldefense.com/v3/__https://docs.mesastar.org/en/latest/about.html*developers__;Iw!!IKRxdwAv5BmarQ!dFfyYL414f_nuyOgsnLUOCwR73pHNQ0WutdCYaJKVaWvAyNBAlVyNV98jydPqr2KuL2IuK6aDwXNeiNT6CLxTRCt$>:
Warrick Ball, Evan Bauer, Earl Bellinger, Lars Bildsten, Matteo Cantiello,
Matthias Fabry, Ebraheem Farag, Eoin Farrell, Meridith Joyce, Pablo
Marchant, Joey Mombarg, Radek Smolec, Anne Thoul, Frank Timmes, Rich
Townsend, & Bill Wolf
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