Oscillations on the Sun in regions with a vertical magnetic field

I. Sunspot umbral oscillations

Central Astronomical Observatory of Russian Academy of Sciences, 65 Pulkovo, 196 140 St. Petersburg, Russia

Corresponding author: zhukov-spb@mail.ru

Received: 29 August 2001
Accepted: 29 January 2002

Abstract

We have calculated the spectrum of eigenmodes of umbral oscillations. The eigenmodes of oscillations with periods from several tens of minutes (g-modes) to several tens of seconds (p-modes) have been found. It is shown that the 3-min umbral oscillations are p-modes modified by the magnetic field.