천문학회보 (The Bulletin of The Korean Astronomical Society)
- 제38권1호
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- Pages.61.2-61.2
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- 2013
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- 1226-2692(pISSN)
Chromospheric Sunspot Oscillations in H-alpha and Ca II 8542A
초록
We study chromospheric oscillations including umbral flashes and running penumbral waves in a sunspot 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.
키워드