# R_CrB_star¶

This test case creates and evolves a simple model of an R Corona Borealis star. The model is constructed from an 0.875 $${\rm M}_\odot$$ homogeneous He star and evolved until it first reaches a low effective temperature. The calculation is based on the Schwab (2019) reproduction of the work of Weiss (1987).

This test suite provides an example of how to use AESOPUS opacity tables in MESA. See $MESA_DIR/kap/preprocessor/AESOPUS/README for more information. The (xz compressed) directory RCrB_GS98 contains the opacity files obtained from the webform. The preprocessing steps tar xf RCrB_GS98.tar.xz$MESA_DIR/kap/preprocessor/AESOPUS/aesopus.py RCrB_GS98.yaml


generated the AESOPUS_GS98_RCrB.h5 file. This is the opacity file that is read by MESA. The .dat files in the RCrB_GS98 tarball are included only to demonstrate the workflow.

The commands that configure the opacity tables are in inlist_common.

This test case has 3 parts, but by default, saved models are used to skip to part 3. Options shared between all parts are contained in inlist_common.

• Part 1 (inlist_He_star) creates a hydrogen-free initial model and evolves it from the pre-main-sequence through He core burning until there is less than 0.45 $${\rm M}_\odot$$ of He remaining in the envelope.
• Part 2 (inlist_change_abundances) manually alters the envelope composition so that it has a carbon-enhanced composition, corresponding to mixture R2 in Weiss (1987). It then evolves the model until the envelope begins to expand and the effective temperature falls to 20,000 K.
• Part 3 (inlist_R_CrB_star) evolves the models from effective temperature 20,000 K to 6,000 K so that the outer layers cross the opacity blend from the OPAL opacities to the AESOPUS opacities.

Last-Updated: 2020-11-16 (mesa r14909) by Josiah Schwab