Statistical Characteristics of Umbra Oscillation of Sunspots in Ca Band
Abstract
Hinode telescope observed a series of successive sunspot evolution images on March 4, 2014 under the Ca II H (396.85 nm) line. The calculated oscillation period of sample point is 149.75 s by using the Jurkevich method (JK method). A suitable average of the intensity profile is selected as the steady background radiation, then the distribution of the extreme value of the oscillation in umbra is analyzed by statistical method. The results show that the trough is a normal distribution, and the peak is a skewed normal distribution. The distribution of this extreme value indicates that the 3-min oscillation of the umbra may be caused by the propagation of a traveling wave with a period of about 5 min in the umbra. The variation of the light intensity caused by the traveling wave may be proportional to the square of the displacement of the traveling wave, resulting in a 3-min period of the light intensity which is half of the period of traveling wave.
- Publication:
-
Acta Astronomica Sinica
- Pub Date:
- May 2018
- Bibcode:
- 2018AcASn..59...26H
- Keywords:
-
- Sun: oscillations;
- Sun: sunspots;
- methods: statistical