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D. B. Seaton (Harvard-Smithsonian Center for Astrophysics), J. M. Pasachoff, B. A. Babcock, K. D. Russell (Hopkins Observatory, Williams College)
As a part of a study of the cause of solar coronal heating, we searched at several eclipses for high-frequency (~1 Hz) intensity oscillations in coronal loops in the [Fe XIV] coronal green line. Such oscillations in the 1-Hz range are predicted as a result of density fluctuations from the resonant absorption of MHD waves. The dissipation of a significant amount of mechanical energy from the photosphere into the corona through this mechanism could provide sufficient energy to hear the corona. We summarize results from observations made at the 11 August 1999 total solar eclipse from Râmnicu-Vâlcea, Romania, through clear skies, where data were taken through two simultaneous series of coronal CCD images digitized at 10 Hz for a total time of about 140 s. Previous observations, described in Pasachoff, Babcock, Russell, McConnochie, and Diaz (2000), had a detection limit of 2% for intensity oscillations in the [Fe XIV] green line. We found stronger coronal intensity at the 1999 eclipse because of the peak in the sunspot cycle and we selected our region of observations in consultation with SOHO/EIT and TRACE scientists. One series of images was taken through a 3.6 Å filter isolating the 5303 Å [Fe XIV] coronal green line and the other through a 100 Å filter in the nearby K-corona continuum. We used Fourier analysis to search in the [Fe XIV] channel for intensity oscillations in loops at the base of the corona (Pasachoff, Babcock, Russell, & Seaton, 2002). A comparison with a Monte-Carlo model of the data suggested the presence of enhanced power, particularly in the 0.75-1.0 Hz range. We report on our ongoing wavelet analysis that may make a stronger case for the presence of oscillations in our data. We also discuss plans for observing the 4 December 2002 eclipse.
Support for this research has been provided by the National Science Foundation, the National Geographic Society, and NASA; DBS is supported by the TRACE grant, contract NAS5-38099 from NASA to LMATC.
The author(s) of this abstract have provided an email address for comments about the abstract: dseaton@cfa.harvard.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.