22–27 Sept 2025
INAF, Osservatorio Astronomico di Roma
Europe/Rome timezone

Frequency stability of solar acoustic oscillations near the photospheric cut-off

23 Sept 2025, 17:05
25m
Aula Gratton (INAF, Osservatorio Astronomico di Roma)

Aula Gratton

INAF, Osservatorio Astronomico di Roma

Via Frascati, 33, 00078 Monteporzio Catone (RM)
Invited Talk Invited Talk

Speaker

Dmitrii Kolotkov (University of Warwick)

Description

Acoustic waves below the cut-off frequency reflect at the photosphere, forming standing p-modes in sub-photospheric cavities. Above the cut-off, waves propagate as pseudomodes. Recent observations show pseudomode frequencies vary in anti-phase with the 11-year solar cycle, which is not yet fully explained. Using the Klein-Gordon equation with a piecewise acoustic potential, we study the frequency stability of trapped p-modes and propagating pseudomodes, influenced by the acoustic cut-off and wave source location. P-mode frequencies decrease due to the cut-off effect but are insensitive to source depth. Linking the cut-off to the plasma β parameter, we show that solar cycle modulation of the photospheric magnetic field can explain observed p-mode frequency shifts. Pseudomode frequencies, however, depend on both the cut-off effect and source depth. Our model qualitatively reproduces the observed anti-phase variation of pseudomode frequencies with the solar cycle.

Presentation materials

There are no materials yet.