Oscillations

• Recording.
• PowerPoint presentation. In Czech only.
• Hand-written notes.
• Notes from David Korda, in Czech, a very nice study material on oscillations and helioseismology basically following the lecture. He has very nice figures on aliasing and issues of frequency analysis. Reading and following this is very recommended.

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• Correction: fundamental mode.
• Alternative derivation of the f-mode: page 1 and page 2.

• Oscillations on the Sun are the observational fact. They can be recorded in may observables (intensity, line-of-sight velocity, and others) and a simple application of the dicrete Fourier transform reveals that there are indeed standing waves present on the Sun. One need to keep in mind that the application of DFT has its limits.
• The derivation of the dispersion relations is lenghty, but it can be followed step by step.
• Three different types of waves in the Sun. Internal gravity (g-) modes that typically have a Brunt-Vaisala frequency, the acoustic (presure, p-) modes that propagate mostly in the convection zone of the Sun and are triggered by the surface convection, and surface gravity (f-) modes that are similar to waves on a free ocean surface.
• The waves propages in the gravitationally statified medium, hence their propagation follows some trajectory. Some of the waves with a diagnostic potential are captured in the resonnance cavity. They have two reflection points, one at depth (the depth depends on the angular degree l and the frequency of the given mode) and one at the surface.