Volume 369, Number 2, April II 2001
|Page(s)||660 - 671|
|Section||Planets and planetary systems|
|Published online||15 April 2001|
Five-minute oscillations above granules and intergranular lanes
Main Astronomical Observatory, National Academy of Sciences, 03680 Kyiv-127, Ukraine
Corresponding author: R. I. Kostik, email@example.com
Accepted: 17 January 2001
We discuss the links between the photospheric 5-min oscillations and the granulation pattern using a 30-min time series of CCD spectrograms of solar granulation recorded with high spatial (0´´5) and temporal (9.3 s) resolution. The observed images contain the Fe i 5324 Åspectral line with good height coverage from the low photosphere up to the temperature minimum region. Amplitudes, phases and periods of the 5-min oscillations are found to be different above granules and intergranular lanes. Strong oscillations occur well separated temporally and spatially. Many features of this different behaviour can be described in the frame of a relatively simple model of wave propagation in the solar atmosphere. To that aim, we have introduced oscillations into a 3D snapshot of a theoretical time dependent solar model atmosphere. NLTE synthesis of the time series of the Fe i 5324 Åline profiles was performed taking into account granular and oscillatory components of the velocity field. Both, observations and theoretical modeling, lead to similar results: (i) oscillations above granules and intergranular lanes occur with different periods; (ii) the most energetic intensity oscillations occur above intergranular lanes; the most energetic velocity oscillations occur above granules and lanes with maximum contrast, i.e. above the regions with maximum convective velocities; (iii) velocity oscillations at the lower layers of the atmosphere lead oscillations at the upper layers in intergranular lanes. In granules the phase shift is nearly zero. We conclude that differences in oscillations above granules and lanes are caused mainly by variations of the physical conditions in these structures.
Key words: Sun: photosphere / Sun: granulation / Sun: oscillations
© ESO, 2001
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.