polytropic

This is a small code for solving linear perturbations of stars, which follows the code GYRE (https://gyre.readthedocs.io/en/stable/), but solved complex eigenvalues in a new way. See arXiv:2203.11809.

What the code can do

Make a polytropic star with rotation to the lowest order (as a function of only radius), a "rotational profile" (not exactly the same thing) must be given.
Solve non-adiabatic non-radial modes of linear perturbations.
Low-viscosity perturbations as shown in arXiv:2203.11809.
Read mesa files.

What the code can potentially do

Implement adiabatic and/or radial mode calculations.
Solve other similar linear eigenvalue problems.
For science backgrounds, also see https://gyre.readthedocs.io/en/stable/.

Caveats

There are speed optimizations for matrix determinant calculation, but not for matrix construction. This can improve the speed significantly.
Jump conditions are not included yet.

The demo notebook

The notebook can produce Figs. 1, 2 (with low_viscosity=True), 3, &4 (with low_viscosity=False) of arXiv:2203.11809.
The total run time is ~20 min (Intel Core i7-1065G7) for each, due to lack of optimization.

Citations, if it's useful

https://ui.adsabs.harvard.edu/abs/2022arXiv220311809S/abstract

@ARTICLE{ShiFuller2022,
       author = {{Shi}, Yanlong and {Fuller}, Jim},
        title = "{Viscous and centrifugal instabilities of massive stars}",
      journal = {arXiv e-prints},
     keywords = {Astrophysics - Solar and Stellar Astrophysics},
         year = 2022,
        month = mar,
          eid = {arXiv:2203.11809},
        pages = {arXiv:2203.11809},
archivePrefix = {arXiv},
       eprint = {2203.11809},
 primaryClass = {astro-ph.SR},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2022arXiv220311809S},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

yanlongastro / polytropic