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Infrared Helioseismology: Detection of the chromospheric mode

Published online by Cambridge University Press:  03 August 2017

Drake Deming
Affiliation:
Planetary Systems Branch, Code 693, Goddard Space Flight Center, Greenbelt, MD 20771
David A. Glenar
Affiliation:
Department of Physics, Colgate University, Hamilton, NY 13346
Hans Ulrich Käufl
Affiliation:
Planetary Systems Branch, Code 693, Goddard Space Flight Center, Greenbelt, MD 20771
Fred Espenak
Affiliation:
Planetary Systems Branch, Code 693, Goddard Space Flight Center, Greenbelt, MD 20771

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We have observed solar oscillations using a new instrumental technique in a relatively unexplored region of the solar spectrum. We obtained a 2-day sequence of line profiles, at 30 second intervals, for a pure rotation line of OH at 11.065 μm, using a laser heterodyne spectrometer to view a 2 arc-sec portion of the quiet Sun at disk center. The continuous opacity of the solar atmosphere increases with wavelength longward of 1.6 μm, so 11 μm lines are formed in the upper photosphere, near h = 250 km. In this region the OH rotational transitions have δJ=1 collisional rates which are two orders of magnitude larger than their radiative rates. Hence the OH lines have source functions which are equal to the Planck function, and the high spectral purity provided by the laser heterodyne technique makes their line profiles especially appropriate for investigating the dynamics of the solar atmosphere. We have recently reported (Deming et al. 1986) that oscillations in this OH line show evidence of a resonance due to a cavity in the solar chromosphere.

Type
Chapter 7: Oscillations in the Solar Atmosphere
Copyright
Copyright © Reidel 1988 

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