Feature comparison

This page gives an overview of the features that StORM supports and for which cases you might want to use other oscillation codes.

Input data

StORM currently only supports the GSM format. If you have other stellar model formats that you want to use with StORM, see if tomso is able to import the format you have and convert it to a GSM. While StORM might be able to read more types of models in the future, this is currently a low priority given tools such as tomso exist.

Included physics

StORM only solves the adiabatic pulsation equations [1] with the vacuum boundary conditions [2]. Any form of energy transport through radiation, conduction, … is ignored.

Rotation is included on various levels. A more detailed explanation can be found here. In short, StORM does the following:

• The main solver includes terms for the Coriolis acceleration up to first order

• Toroidal mode coupling in a perturbative way

• Stellar deformation and resulting mode coupling in a perturbative way

The radial order determination is done with Eckart-Scuflaire-Osaki-Takata scheme.

Some features you might want, but are not supported

• Automatic regridding in case the stellar model resolution is low (manually increasing the number of points is supported as part of the input command)

• Non-adiabatic calculations

• Full 2D stellar models (e.g. such as done by ACOR and TOP) and pulsation calculations

• Traditional approximation of rotation for high-order g modes with rotation

• Effects of magnetic fields

These features may be supported in the future.

[1]

Derivations for the adiabatic pulsation equations can be found in various textbooks. An overview of the equations can be found in the GYRE documentation. Note that StORM uses a modified form of the equations to partial include the effect of the Coriolis force in the main solver, similar to Soufi et al. (1998). Validation of the results can be found in maxima/oscillation-equations.mac.

[2]

This assumes that the pressure goes to zero near the surface of the star. Should the density not go to zero, the outer boundary is treated as having a density discontinuity, immediately dropping to zero outside the star.