Astrophysics and Space Science
Volume 170, Numbers 1-2, 43-45, DOI: 10.1007/BF00652642

Sun and Sun-Like Stars

Penumbral oscillations in Na D lines

E. Marco and W. Mattig

From the issue entitled "New windows to the universe"

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Abstract

Penumbral oscillations were measured in two opposite parts in the penumbra of a spot, using photographic spectra of Na D lines. Power spectra of velocities show the presence of the 5-min oscillation with lowv rms.
Coherence and phase analyses between the velocity fluctuations of the lines are also studied.
The results seem to show that the 5-min oscillation is still surviving as a standing or evanescent wave at the height of formation of Na D lines.
Paper presented at the 11th European Regional Astronomical Meetings of the IAU on lsquoNew Windows to the Universersquo, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.

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