The study of umbral dots in sunspots based on SOT/Hinode observations

Abstract

To understand the energy transport in sunspots, it is necessary to investigate the dynamic properties of umbral dots (UDs). In this connection, we used high-resolution SOT/Hinode time-series images. The intensity oscillations of UDs are determined. We conclude that their periods are in the range of 3-5 min, which may be related to the propagation of p-modes through them. We follow the motion path of UDs and investigate whether they are oscillating quasi-periodically. Moreover, we detect their transverse motion and obtain two different periods for these oscillations. Finally, we analyze the diameter of UDs as circular spots. We find that the UDs fluctuate in size.