Bibcode
Sánchez Cuberes, M.; Vázquez, M.; Bonet, J. A.; Sobotka, M.
Bibliographical reference
Astronomy and Astrophysics, v.397, p.1075-1081 (2003)
Advertised on:
1
2003
Journal
Citations
11
Refereed citations
9
Description
Broad-band images have been obtained at the extremes of the continuum
absorption coefficient of the solar atmosphere, at lambda 0.8 mu m and
lambda 1.55 mu m. Quiet regions have been observed for different
heliocentric angles. The centre-to-limb variation of granulation
contrast has been computed in both wavelength ranges and a steeper
decrease in the contrast is obtained for lambda 0.8 mu m than for lambda
1.55 mu m. For positions near the solar limb the granulation contrast
shows a tendency to increase at both wavelengths. Mean granular sizes
vary from 1.25 arcsec2 at the disc centre to 2
arcsec2 at mu =0.6 in the lambda 0.8 mu m images and from
1.24 arcsec2 to 1.85 arcsec2 at lambda 1.55 mu m.
Observations close to the limb detect granular structures of 0.arcsec
96 or even smaller at a distance from the limb of d= 0.arcsec 32, equal
to the diffraction limit of the telescope at lambda 8000 Å. Using
an Eddington-Barbier approximation this implies a penetration of the
temperature fluctuations associated with granulation up to approximately
z ~ 220 km, although the calculation of response functions defines a
broader interval.