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Spatial power-spectra from Yohkoh soft X-ray imagesWe analyze three sequences of images from active regions, and a full disk image obtained by Yohkoh's Soft X-ray Telescope. Two sequences are from a region at center disk observed through different filters, and one sequence is from the limb. After Fourier-transforming the X-ray intensity of the images we find nearly isotropic power-spectra with an azimuthally integrated slope of -2.1 for the center disk, and -2.8 for the limb images. The full-disk picture yields a spectrum of -2.4. These results are different from the active region spectra obtained with the Normal Incidence X-ray Telescope which have a slope of the order of -3.0, and we ascribe this to the difference in temperature response between the instruments. However, both the SXT and NIXT results are consistent with coronal heating as the end result of a downward quasistatic cascade (in lengthscales) of free magnetic energy in the corona, driven by footpoint motions in the photosphere.
Document ID
19930036503
Document Type
Reprint (Version printed in journal)
Authors
Martens, Petrus C. H. (Lockheed Research Labs. Palo Alto, CA, United States)
Gomez, Daniel O. (Hawaii Univ. Honolulu, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1992
Publication Information
Publication: PASJ: Publications of the Astronomical Society of Japan
Volume: 44
Issue: 5
ISSN: 0004-6264
Subject Category
SOLAR PHYSICS
Funding Number(s)
CONTRACT_GRANT: NAGW-864
CONTRACT_GRANT: NAS8-37334
Distribution Limits
Public
Copyright
Other