Slow magnetoacoustic gravity waves in an equilibrium stratified solar atmosphere: cut-off periods through the transition region

A. COSTA, M. SCHNEITER, E. ZURBRIGGEN

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

0035-8711

We introduce a temperature dependent model that contemplates the magneticfield and a non-uniform medium due to the stratification caused by gravity, allowing the study of cut-off periods across the solar transition region, from the base of the solar chromosphere to the lower corona. The analytical model is employed with a temperature profile that approaches the VAC solar atmospheric model. The periods obtained are consistent with the observations. Similar to the acoustic cut-off periods, the resulting magnetoacoustic gravity ones follow the sharp temperature profile, but shifted towards larger heights; in other words, at a given height the magnetoacoustic cut-off period is significantly lower than the corresponding acoustic one. As recent literature results we find that the more inclined the magnetic tube the larger thecut-off period. Also, along a given longitude of a thin magnetic tube, the greater its inclination the softener the temperature gradient it crosses. Changes in the magnetic field intensity do not significantly modify the periods at the coronal level but can modulate the values before the transition region within periods between ∼ 2 min and∼ 6 min. Within the limitations of our model, we show that the cut-off period is the response of the different atmospheric layers at its natural frequency to random perturbations.