[Mesa-users] New public release 11532

Rob Farmer r.j.farmer at uva.nl
Tue Mar 5 14:16:48 EST 2019


Dear MESA Users,

To coincide with the new mesa instrument paper we’re happy to announce a
new public release of MESA: version 11532. We refer the reader to the paper
for the largest and most significant changes. Here we give a brief overview
of the changes from the MESA paper as well as document the changes which
did not make it to the instrument paper.

https://arxiv.org/abs/1903.01426

Inlists available on mesastar.org and https://zenodo.org/communities/mesa/


Thanks,
Rob (on behalf of the MESA developer team)


MESA 11532 Release Notes:

We welcome the following new MESA developers:

Adam Jermyn

Radek Smolec

RSP is a new functionality in MESAstar that models the non-linear radial
stellar pulsations that characterize RR Lyrae, Cepheids, and other classes
of variable stars. See the rsp_* examples in the test suite.

We significantly enhance numerical energy conservation capabilities,
including during mass changes. For example, this enables calculations
through the He flash that conserve energy to better than 0.001%. Most test
cases now have this enabled, for instance 1.3M_ms_high_Z,
25M_pre_ms_to_core_collapse, and wd as examples.

To improve the modeling of rotating stars in MESA, we introduce a new
approach to modifying the pressure and temperature equations of stellar
structure, and a formulation of the projection effects of gravity
darkening. The latter are controlled by the grav_dark options in
history_columns.list;  see high_rot_darkening for an example of its use.

A new scheme for tracking convective boundaries, called Convective
Pre-Mixing (CPM), yields reliable values of the convective-core mass, and
allows the natural emergence of adiabatic semiconvection regions during
both core hydrogen- and helium-burning phases. Examples for this can be
found in the inlists provided with the mesa 5 paper.

We have updated the equation of state and nuclear reaction physics modules.

There are an increased number of warnings for when MESA goes beyond the
validity of the input physics (for instance the nuclear reactions rates
from REACLIB are ill-defined when logT>10.0). These warnings are controlled
by the warn_* options.

The definition of eps_nuc has slightly changed (see MESA V, Section 3.2) in
order to be suitable for use with the new energy equation.  If you are
running models using the dLdm form that includes eps_grav, you should
consult the controls option include_composition_in_eps_grav and its
associated documentation.

A new set of tests (gyre_in_mesa_*) demonstrate how to call GYRE on the fly
during a MESA run.

The astero module now allows users to define model parameters
(my_param[123]) that will be optimised in a similar way to the standard
options (M, Y, FeH, alpha, f_ov). These are defined in the subroutine
set_my_params in run_star_extras.f in a similar way to how users can define
their own observables (my_var[123]).

The astero module now has controls normalize_chi2_* that allow the user to
decide whether or not to normalize each component of χ² by the number of
terms that contributed to that component.

The format of the OP_MONO opacity table cache has changed.  If you have
used these files in a previous version of MESA then you should do:

   rm $MESA_OP_MONO_DATA_CACHE_FILENAME

before installing MESA.  If you use multiple MESA versions, this means that
you cannot share the cache file between old and new versions.  Therefore,
you should make sure to use a different cache file in each case. This may
be more easily accomplished using the controls option
op_mono_data_cache_filename rather than the environment variable.

The version of GYRE bundled with MESA has been updated to version 5.2

Binaries can now model “twins”, where we can skip the calculation of the
companion as its assumed to be identical to the primary. This is controlled
by the binary_job parameter *_model_twins_flag

There is a new way to treat convection in a model, via the
convective_velocity_flag. This adds an equation to solve the velocity of
convective motion, instead of using the value derived from MLT. This is
useful for models evolving on fast timescales and is a replacement for
min_T_for_acceleration_limited_conv_velocity

Two new test cases (hydro_Ttau_solar and hydro_Ttau_evolve) demonstrate the
use of mixing length parameters and T(tau) relations calibrated to 3D
radiation-coupled hydrodynamics (RHD) simulations computed by Trampedach et
al. (2014). More details are provided in Mosumgaard et al. (2018). MESA
also includes low-temperature opacity tables that match those used in the
3D RHD simulations, which can be used by setting kappa_lowT_prefix =
'lowT_rt14_ag89'

There have been many bug fixes and performance enhancements to MESA.
Reports of bugs or suggested improvements are welcome on the mesa-users
mailing list.

A reminder to please share your inlists and run_star_extras on mesastar.org
upon publication of your science papers!
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