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arXiv · 0709.0569

Observations of Sunspot Oscillations in G band and Ca II H line with Solar Optical Telescope on Hinode

Kaori Nagashima·Takashi Sekii·Alexander G. Kosovichev·Hiromoto Shibahashi·Saku Tsuneta·Kiyoshi Ichimoto·Yukio Katsukawa·Bruce W. Lites·Shin'ichi Nagata·Toshifumi Shimizu·Richard A. Shine·Yoshinori Suematsu·Theodore D. Tarbell·Alan M. Title
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Abstract

Exploiting high-resolution observations made by the Solar Optical Telescope onboard Hinode, we investigate the spatial distribution of power spectral density of oscillatory signal in and around NOAA active region 10935. The G-band data show that in the umbra the oscillatory power is suppressed in all frequency ranges. On the other hand, in Ca II H intensity maps oscillations in the umbra, so-called umbral flashes, are clearly seen with the power peaking around 5.5 mHz. The Ca II H power distribution shows the enhanced elements with the spatial scale of the umbral flashes over most of the umbra but there is a region with suppressed power at the center of the umbra. The origin and property of this node-like feature remain unexplained.

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Kaori Nagashima, Takashi Sekii, Alexander G. Kosovichev, Hiromoto Shibahashi, Saku Tsuneta, Kiyoshi Ichimoto, Yukio Katsukawa, Bruce W. Lites, Shin'ichi Nagata, Toshifumi Shimizu, Richard A. Shine, Yoshinori Suematsu, Theodore D. Tarbell, Alan M. Title. 2007-09-05. Observations of Sunspot Oscillations in G band and Ca II H line with Solar Optical Telescope on Hinode. https://doi.org/10.1093/pasj%2F59.sp3.s631

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