Bibcode
Kostik, R.; Khomenko, E.; Shchukina, N.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 506, Issue 3, 2009, pp.1405-1414
Fecha de publicación:
11
2009
Revista
Número de citas
31
Número de citas referidas
29
Descripción
Aims: The purpose of this paper is to characterize the statistical
properties of solar granulation in the photosphere and low chromosphere
up to 650 km. Methods: We use velocity and intensity variations
obtained at different atmospheric heights from observations in Ba II
4554 Å. The observations were done during good seeing conditions
at the VTT at the Observatorio del Teide on Tenerife. The line core
forms rather high in the atmosphere and allows granulation properties to
be studied at heights that have been not accessed before in similar
studies. In addition, we analyze the synthetic profiles of the Ba II
4554 Å line by the same method computed taking NLTE effects into
account in the 3D hydrodynamical model atmosphere. Results: We
suggest a 16-column model of solar granulation depending on the
direction of motion and on the intensity contrast measured in the
continuum and in the uppermost layer. We calculate the heights of
intensity contrast sign reversal and velocity sign reversal. We show
that both parameters depend strongly on the granulation velocity and
intensity at the bottom photosphere. The larger the two parameters, the
higher the reversal takes place in the atmosphere. On average, this
happens at about 200-300 km. We suggest that this number also depends on
the line depth of the spectral line used in observations. Despite the
intensity and velocity reversal, about 40% of the column structure of
granulation is preserved up to heights around 650 km.
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