Astronomy and Astrophysics – Astrophysics
Scientific paper
Aug 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995a%26a...300..539k&link_type=abstract
Astronomy and Astrophysics, v.300, p.539
Astronomy and Astrophysics
Astrophysics
13
Sun: Chromosphere, Sun: Oscillations, Sunspots
Scientific paper
Long time series of two dimensional filtergrams of the chromosphere above a sunspot in the line cores of Hα (λ656.2nm), CaIIK (λ393.3nm) and in MgIb (λ517.3nm) were recorded simultaneously. The following conclusions can be drawn: The Power spectra of Hα and CaIIK show two distinct distributions between 5 and 9mHz. The first peak at 5.9mHz is relatively narrow (FWHM=1.2mHz) and consists mainly of upward propagating waves travelling with sound speed (7km/s). There are indications that the oscillations found in this frequency domain have their origin in the underlaying layers. Therefore this first distribution may be a fingerprint of the photospheric resonator. A phase analysis of the horizontal propagations of the oscillations yields a typical inclination of the magnetic field lines in the umbral chromosphere of 5deg. A second distribution at 7.5mHz has a width of 3.3mHz. The involved oscillations have characteristics of standing waves. There is no correlation between the oscillations found in the chromosphere and these, located near the temperature minimum layers, so they are confined to the chromosphere itself.
Kentischer Th. J.
Mattig Wolfgang
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