Comparison of exact and approximate MHD slow body mode solutions in photospheric waveguides

TL;DR

This paper compares exact and approximate models of MHD slow body modes in photospheric waveguides, demonstrating that simplified boundary conditions can accurately replicate more complex models with less than 1% error.

Contribution

It introduces a simplified modeling approach for MHD slow body modes that neglects certain boundary conditions without significant loss of accuracy.

Findings

Simplified boundary conditions yield less than 1% error in modeling.

The approach aligns well with observational data.

Neglecting certain boundary conditions simplifies the modeling process.

Abstract

In this study we explore the possibility of simplifying the modeling of magnetohydrodynamic (MHD) slow body modes observed in photospheric magnetic structure such as the umbrae of sunspots and pores. The simplifying approach assumes that the variation of the eigenvalues of slow body waves can be derived by imposing that the longitudinal component of velocity with respect to the tube axis is zero at the boundary of the magnetic flux tube, which is in a good agreement with observations. To justify our approach we compare the results of our simplified model for slow body modes in cylindrical flux tubes with the model prediction obtained by imposing the continuity of the radial component of the velocity and total pressure at the boundary of the flux tube. Our results show that, to a high accuracy (less than 1\% for the considered model), the conditions of continuity of the component of transversal velocity and pressure at the boundary can be neglected when modelling slow body modes under photospheric conditions.