Main category

Natural Sciences (Astrophysics and Astrononmy)

Abstract

Direct evidence for the existence of an acoustic cuto frequency in the solar atmosphere is given by observations performed by using the HELioseismological Large Regions Interferometric DEvice operating on the Vacuum Tower Telescope located on Tenerife. The observational results demonstrate variations of the cuto  with atmospheric heights. The observed variations of the cuto are compared to theoretical predictions made by using ve acoustic cuto frequencies that have been commonly used in helioseismology and asteroseismology. The comparison shows that none of the theoretical predictions is fully consistent with the observational data. The implication of this nding is far reaching as it urgently requires either major revisions of the existing methods of nding acoustic cuto frequencies or developing new methods that would account much better account for the physical picture underlying the concept of cuto frequencies in inhomogeneous media.

DOI

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Link this paper

https://science-media.org/paper/64