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Infrared Helioseismology: Detection of the chromospheric mode
Published online by Cambridge University Press: 03 August 2017
Extract
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
- Information
- Symposium - International Astronomical Union , Volume 123: Advances In Hello- and Asteroseismology , 1988 , pp. 425 - 428
- Copyright
- Copyright © Reidel 1988