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arXiv · 1302.1234

Chromospheric Sunspot Oscillations in H-alpha and Ca II 8542A

Ram Ajor Maurya·Jongchul Chae·Hyungmin Park·Heesu Yang·Donguk Song·Kyuhyoun Cho
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Abstract

We study chromospheric oscillations including umbral flashes and running penumbral waves in a sunspot of active region (AR) using scanning spectroscopy in H-alpha and Ca II 8542A, with the Fast Imaging Solar Spectrograph (FISS) at the 1.6 meter New Solar Telescope at Big Bear Solar Observatory. A bisector method is applied to spectral observations to construct chromospheric Doppler velocity maps. Temporal sequence analysis of these shows enhanced high-frequency oscillations inside the sunspot umbra in both lines. Their peak frequency gradually decreases outward from the umbra. The oscillation power is found to be associated with magnetic-field strength and inclination, with different relationships in different frequency bands.

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Ram Ajor Maurya, Jongchul Chae, Hyungmin Park, Heesu Yang, Donguk Song, Kyuhyoun Cho. 2013-02-06. Chromospheric Sunspot Oscillations in H-alpha and Ca II 8542A. https://arxiv.org/abs/1302.1234

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