Observations of a large solar flare of December 13, 2006, using Solar Optical Telescope (SOT) on Hinode spacecraft revealed high-frequency oscillations excited by the flare in the sunspot chromosphere. These oscillations are observed in the region of strong magnetic field of the sunspot umbra, and may provide a new diagnostic tool for probing the structure of sunspots and understanding physical processes in solar flares.
@article{arxiv.0710.1808,
title = {Initial Observations of Sunspot Oscillations Excited by Solar Flare},
author = {A. G. Kosovichev and T. Sekii},
journal= {arXiv preprint arXiv:0710.1808},
year = {2009}
}