Seismology of the solar atmosphere

Issue Title: The physics of solar and solar-like oscillations; guest editors T. Bedding and J. Leibacher We describe a new instrument for seismically probing the properties of the Sun's lower atmosphere, and present some first results from an observational campaign carried out at the geographic...

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Bibliographic Details
Published in:	Solar physics Vol. 220; no. 2; pp. 317 - 331
Main Authors:	Finsterle, Wolfgang, Jefferies, Stuart M., Cacciani, Alessandro, Rapex, Paolo, Giebink, Cynthia, Knox, Allister, DiMartino, Vincenzo
Format:	Journal Article
Language:	English
Published:	Dordrecht Springer Nature B.V 01-04-2004
Subjects:	Atmosphere Magnetic fields Seismology Solar physics Sound waves Sun Sunspots Antarctica, South Pole
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Summary:	Issue Title: The physics of solar and solar-like oscillations; guest editors T. Bedding and J. Leibacher We describe a new instrument for seismically probing the properties of the Sun's lower atmosphere, and present some first results from an observational campaign carried out at the geographic South Pole during the austral summer of 2002/2003. A preliminary analysis of the data (simultaneous, high-cadence observations of the velocity signals from the photosphere and low chromosphere) shows that the well-known suppression of acoustic power in regions of strong magnetic field, and enhancement of high-frequency power around active regions (acoustic halos), are both consistent with a spreading out of the magnetic field lines with increasing height in the atmosphere. The data have also revealed some unexpected wave behavior. First, evanescent-like waves are found at frequencies substantially above the acoustic cut-off frequency in regions of intermediate magnetic field. Second, upward- and downward-propagating waves are detected in areas of strong magnetic field such as sunspots and plage: even at frequencies below the acoustic cut-off frequency. Third, the wave behavior in regions of strong magnetic field can change over periods of a few hours from propagating to evanescent. While we have no concrete explanation for the first two results, the latter result opens up the question of whether sound waves are involved in short-term events such as flares or CME's.[PUBLICATION ABSTRACT]
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0038-0938 1573-093X
DOI:	10.1023/B:SOLA.0000031397.73790.7b