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Title: Photospheric Origin of Three-minute Oscillations in a Sunspot

Abstract

The origin of the three-minute oscillations of intensity and velocity observed in the chromosphere of sunspot umbrae is still unclear. We investigated the spatio-spectral properties of the 3 minute oscillations of velocity in the photosphere of a sunspot umbra as well as those in the low chromosphere using the spectral data of the Ni i λ 5436, Fe i λ 5435, and Na i D{sub 2} λ 5890 lines taken by the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. As a result, we found a local enhancement of the 3 minute oscillation power in the vicinities of a light bridge (LB) and numerous umbral dots (UDs) in the photosphere. These 3 minute oscillations occurred independently of the 5 minute oscillations. Through wavelet analysis, we determined the amplitudes and phases of the 3 minute oscillations at the formation heights of the spectral lines, and they were found to be consistent with the upwardly propagating slow magnetoacoustic waves in the photosphere with energy flux large enough to explain the chromospheric oscillations. Our results suggest that the 3 minute chromospheric oscillations in this sunspot may have been generated by magnetoconvection occurring in themore » LB and UDs.« less

Authors:
; ; ;  [1]; ;  [2]
  1. Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of)
  2. Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22663879
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 836; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; CHROMOSPHERE; HYDRODYNAMICS; IRON; MAGNETIC FIELDS; MAGNETOACOUSTIC WAVES; MAGNETOACOUSTICS; NICKEL; OSCILLATIONS; PHOTOSPHERE; SODIUM; SPECTRA; SUN; SUNSPOTS; TELESCOPES; VELOCITY; VISIBLE RADIATION

Citation Formats

Chae, Jongchul, Lee, Jeongwoo, Cho, Kyuhyoun, Song, Donguk, Cho, Kyungsuk, and Yurchyshyn, Vasyl. Photospheric Origin of Three-minute Oscillations in a Sunspot. United States: N. p., 2017. Web. doi:10.3847/1538-4357/836/1/18.
Chae, Jongchul, Lee, Jeongwoo, Cho, Kyuhyoun, Song, Donguk, Cho, Kyungsuk, & Yurchyshyn, Vasyl. Photospheric Origin of Three-minute Oscillations in a Sunspot. United States. doi:10.3847/1538-4357/836/1/18.
Chae, Jongchul, Lee, Jeongwoo, Cho, Kyuhyoun, Song, Donguk, Cho, Kyungsuk, and Yurchyshyn, Vasyl. Fri . "Photospheric Origin of Three-minute Oscillations in a Sunspot". United States. doi:10.3847/1538-4357/836/1/18.
@article{osti_22663879,
title = {Photospheric Origin of Three-minute Oscillations in a Sunspot},
author = {Chae, Jongchul and Lee, Jeongwoo and Cho, Kyuhyoun and Song, Donguk and Cho, Kyungsuk and Yurchyshyn, Vasyl},
abstractNote = {The origin of the three-minute oscillations of intensity and velocity observed in the chromosphere of sunspot umbrae is still unclear. We investigated the spatio-spectral properties of the 3 minute oscillations of velocity in the photosphere of a sunspot umbra as well as those in the low chromosphere using the spectral data of the Ni i λ 5436, Fe i λ 5435, and Na i D{sub 2} λ 5890 lines taken by the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. As a result, we found a local enhancement of the 3 minute oscillation power in the vicinities of a light bridge (LB) and numerous umbral dots (UDs) in the photosphere. These 3 minute oscillations occurred independently of the 5 minute oscillations. Through wavelet analysis, we determined the amplitudes and phases of the 3 minute oscillations at the formation heights of the spectral lines, and they were found to be consistent with the upwardly propagating slow magnetoacoustic waves in the photosphere with energy flux large enough to explain the chromospheric oscillations. Our results suggest that the 3 minute chromospheric oscillations in this sunspot may have been generated by magnetoconvection occurring in the LB and UDs.},
doi = {10.3847/1538-4357/836/1/18},
journal = {Astrophysical Journal},
number = 1,
volume = 836,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2017},
month = {Fri Feb 10 00:00:00 EST 2017}
}