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Infrared helioseismology - Detection of the chromospheric modeTime-series observations of an infrared solar OH absorption line profile have been obtained on two consecutive days using a laser heterodyne spectrometer to view a 2 arcsec portion of the quiet sun at disk center. A power spectrum of the line center velocity shows the well-known photospheric p-mode oscillations very prominently, but also shows a second feature near 4.3 mHz. A power spectrum of the line intensity shows only the 4.3 mHz feature, which is identified as the fundamental p-mode resonance of the solar chromosphere. The frequency of the mode is observed to be in substantial agreement with the eigenfrequency of current chromospheric models. A time series of two beam difference measurements shows that the mode is present only for horizontal wavelengths greater than 19 Mm. The period of a chromospheric p-mode resonance is directly related to the sound travel time across the chromosphere, which depends on the chromospheric temperature and geometric height. Thus, detection of this resonance will provide an important new constraint on chromospheric models.
Document ID
19870022925
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Deming, D. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kaeufl, H. U. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Espenak, F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Glenar, D. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hill, A. A. (Colgate University Hamilton, NY, United States)
Date Acquired
August 13, 2013
Publication Date
July 17, 1986
Publication Information
Publication: Nature
Volume: 322
ISSN: 0028-0836
Subject Category
SOLAR PHYSICS
Funding Number(s)
CONTRACT_GRANT: NAG5-478
Distribution Limits
Public
Copyright
Other