Bibcode
                                    
                            Collados, M.; del Toro Iniesta, J. C.; Vazquez, M.
    Referencia bibliográfica
                                    Astronomy and Astrophysics (ISSN 0004-6361), vol. 195, no. 1-2, April 1988, p. 315-326.
Fecha de publicación:
    
                        4
            
                        1988
            
  Número de citas
                                    10
                            Número de citas referidas
                                    9
                            Descripción
                                    The authors present the results of a statistical analysis of the
penumbra of sunspots. The intensity distribution, and several parameters
derived from it, is analysed at different heliocentric angles and
positions on the spot. It has revealed, on the one hand, that a
two-component model is compatible with the observations and that both
components lie at the same height, and on the other, that the penumbral
asymmetry found by Collados et al. (1987) is confirmed under a
photometrical point of view, the western penumbra being slightly shorter
than the eastern one.