A Search for High-Frequency Coronal Brightness Variations in the 21 August 2017 Total Solar Eclipse

P. Rudawy, K. Radziszewski, A. Berlicki, K. J. H. Phillips, D. B. Jess, P. H. Keys, F. P. Keenan

Research output: Contribution to journalArticle

Abstract

We report on a search for short-period intensity variations in the green-line (Fe xiv 530.3 nm) emission from the solar corona during the21 August 2017 total eclipse viewed from Idaho in the United States. Our experiment was performed with a much more sensitive detection system, and with better spatial resolution, than on previous occasions (1999 and 2001 eclipses), allowing fine details of quiet coronal loops and an active-region loop system to be seen. A guided 200-mm-aperture Schmidt-Cassegrain telescope was used with a state-of-the-art CCD camera having 16-bit intensity discrimination and a field-of-view (0.43°× 0.43°) that encompassed approximately one third of the visible corona. The camera pixel size was 1.55 arcseconds, while the seeing during the eclipse enabled features of {≈} 2 arcseconds (1450km on the Sun) to be resolved. A total of 429 images were recorded during a 122.9 second portion of the totality at a frame rate of 3.49s^{-1}. In the analysis, we searched particularly for short-period intensity oscillations and travelling waves, since theory predicts fast-mode magneto-hydrodynamic (MHD) waves with short periods may be important in quiet coronal and active-region heating. Allowing first for various instrumental and photometric effects, we used a wavelet technique to search for periodicities in some 404,000 pixels in the frequency range 0.5 - 1.6 Hz (periods 2 seconds to 0.6 seconds). We also searched for travelling waves along some 65 coronal structures. However, we found no statistically significant evidence in either. This negative result considerably refines the limit that we obtained from our previous analyses, and it indicates that future searches for short-period coronal waves may be better directed towards Doppler shifts as well as intensity oscillations.
LanguageEnglish
Article number48
Number of pages15
JournalSolar Physics
Volume294
DOIs
Publication statusPublished - 01 Apr 2019

Fingerprint

solar eclipses
solar eclipse
brightness
eclipses
traveling waves
corona
pixel
pixels
oscillation
oscillations
coronal loops
solar corona
magnetohydrodynamic waves
field of view
CCD cameras
coronas
wavelet
periodicity
discrimination
periodic variations

Keywords

  • Corona
  • active
  • Heating
  • coronal
  • Waves
  • magnetohydrodynamic
  • plasma
  • propagation

Cite this

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title = "A Search for High-Frequency Coronal Brightness Variations in the 21 August 2017 Total Solar Eclipse",
abstract = "We report on a search for short-period intensity variations in the green-line (Fe xiv 530.3 nm) emission from the solar corona during the21 August 2017 total eclipse viewed from Idaho in the United States. Our experiment was performed with a much more sensitive detection system, and with better spatial resolution, than on previous occasions (1999 and 2001 eclipses), allowing fine details of quiet coronal loops and an active-region loop system to be seen. A guided 200-mm-aperture Schmidt-Cassegrain telescope was used with a state-of-the-art CCD camera having 16-bit intensity discrimination and a field-of-view (0.43°× 0.43°) that encompassed approximately one third of the visible corona. The camera pixel size was 1.55 arcseconds, while the seeing during the eclipse enabled features of {≈} 2 arcseconds (1450km on the Sun) to be resolved. A total of 429 images were recorded during a 122.9 second portion of the totality at a frame rate of 3.49s^{-1}. In the analysis, we searched particularly for short-period intensity oscillations and travelling waves, since theory predicts fast-mode magneto-hydrodynamic (MHD) waves with short periods may be important in quiet coronal and active-region heating. Allowing first for various instrumental and photometric effects, we used a wavelet technique to search for periodicities in some 404,000 pixels in the frequency range 0.5 - 1.6 Hz (periods 2 seconds to 0.6 seconds). We also searched for travelling waves along some 65 coronal structures. However, we found no statistically significant evidence in either. This negative result considerably refines the limit that we obtained from our previous analyses, and it indicates that future searches for short-period coronal waves may be better directed towards Doppler shifts as well as intensity oscillations.",
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doi = "10.1007/s11207-019-1428-4",
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journal = "Solar Physics",
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A Search for High-Frequency Coronal Brightness Variations in the 21 August 2017 Total Solar Eclipse. / Rudawy, P.; Radziszewski, K.; Berlicki, A.; Phillips, K. J. H.; Jess, D. B.; Keys, P. H.; Keenan, F. P.

In: Solar Physics, Vol. 294, 48, 01.04.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A Search for High-Frequency Coronal Brightness Variations in the 21 August 2017 Total Solar Eclipse

AU - Rudawy, P.

AU - Radziszewski, K.

AU - Berlicki, A.

AU - Phillips, K. J. H.

AU - Jess, D. B.

AU - Keys, P. H.

AU - Keenan, F. P.

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N2 - We report on a search for short-period intensity variations in the green-line (Fe xiv 530.3 nm) emission from the solar corona during the21 August 2017 total eclipse viewed from Idaho in the United States. Our experiment was performed with a much more sensitive detection system, and with better spatial resolution, than on previous occasions (1999 and 2001 eclipses), allowing fine details of quiet coronal loops and an active-region loop system to be seen. A guided 200-mm-aperture Schmidt-Cassegrain telescope was used with a state-of-the-art CCD camera having 16-bit intensity discrimination and a field-of-view (0.43°× 0.43°) that encompassed approximately one third of the visible corona. The camera pixel size was 1.55 arcseconds, while the seeing during the eclipse enabled features of {≈} 2 arcseconds (1450km on the Sun) to be resolved. A total of 429 images were recorded during a 122.9 second portion of the totality at a frame rate of 3.49s^{-1}. In the analysis, we searched particularly for short-period intensity oscillations and travelling waves, since theory predicts fast-mode magneto-hydrodynamic (MHD) waves with short periods may be important in quiet coronal and active-region heating. Allowing first for various instrumental and photometric effects, we used a wavelet technique to search for periodicities in some 404,000 pixels in the frequency range 0.5 - 1.6 Hz (periods 2 seconds to 0.6 seconds). We also searched for travelling waves along some 65 coronal structures. However, we found no statistically significant evidence in either. This negative result considerably refines the limit that we obtained from our previous analyses, and it indicates that future searches for short-period coronal waves may be better directed towards Doppler shifts as well as intensity oscillations.

AB - We report on a search for short-period intensity variations in the green-line (Fe xiv 530.3 nm) emission from the solar corona during the21 August 2017 total eclipse viewed from Idaho in the United States. Our experiment was performed with a much more sensitive detection system, and with better spatial resolution, than on previous occasions (1999 and 2001 eclipses), allowing fine details of quiet coronal loops and an active-region loop system to be seen. A guided 200-mm-aperture Schmidt-Cassegrain telescope was used with a state-of-the-art CCD camera having 16-bit intensity discrimination and a field-of-view (0.43°× 0.43°) that encompassed approximately one third of the visible corona. The camera pixel size was 1.55 arcseconds, while the seeing during the eclipse enabled features of {≈} 2 arcseconds (1450km on the Sun) to be resolved. A total of 429 images were recorded during a 122.9 second portion of the totality at a frame rate of 3.49s^{-1}. In the analysis, we searched particularly for short-period intensity oscillations and travelling waves, since theory predicts fast-mode magneto-hydrodynamic (MHD) waves with short periods may be important in quiet coronal and active-region heating. Allowing first for various instrumental and photometric effects, we used a wavelet technique to search for periodicities in some 404,000 pixels in the frequency range 0.5 - 1.6 Hz (periods 2 seconds to 0.6 seconds). We also searched for travelling waves along some 65 coronal structures. However, we found no statistically significant evidence in either. This negative result considerably refines the limit that we obtained from our previous analyses, and it indicates that future searches for short-period coronal waves may be better directed towards Doppler shifts as well as intensity oscillations.

KW - Corona

KW - active

KW - Heating

KW - coronal

KW - Waves

KW - magnetohydrodynamic

KW - plasma

KW - propagation

U2 - 10.1007/s11207-019-1428-4

DO - 10.1007/s11207-019-1428-4

M3 - Article

VL - 294

JO - Solar Physics

T2 - Solar Physics

JF - Solar Physics

SN - 0038-0938

M1 - 48

ER -