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Record Details

Record 7 of 7474
Acoustic absorption by sunspots
External Online Source: doi:10.1086/184949
Author and Affiliation:
Braun, D. C.(Hawaii Univ., Honolulu, HI, United States)
Labonte, B. J.(Hawaii, University, Honolulu, United States)
Duvall, T. L., Jr.(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Abstract: The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity.
Publication Date: Aug 01, 1987
Document ID:
19870062610
(Acquired Nov 28, 1995)
Accession Number: 87A49884
Subject Category: SOLAR PHYSICS
Document Type: Journal Article
Publication Information: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 319; L27-L31
Publisher Information: United States
Contract/Grant/Task Num: NSG-7536
Financial Sponsor: NASA; United States
Organization Source: Hawaii Univ.; Honolulu, HI, United States
NASA Goddard Space Flight Center; Greenbelt, MD, United States
Description: 5p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: PHOTOSPHERE; SOLAR ATMOSPHERE; SOLAR OSCILLATIONS; SOUND WAVES; SUNSPOTS; HANKEL FUNCTIONS; HELIOSEISMOLOGY; PROPAGATION VELOCITY; VIBRATION MODE; WAVE PROPAGATION
Imprint And Other Notes: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X), vol. 319, Aug. 1, 1987, p. L27-L31.
Availability Source: Other Sources
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