The first detailed simulation of the horizontal branch of a Local Group
galaxy (Sculptor dwarf spheroidal galaxy ) will be presented.
It takes consistently into account the star formation history and
metallicity evolution as determined from the
main sequence photometry and red giant branch spectroscopic
observations. The only free parameter is the integrated mass
loss of red giant branch stars. This is the first time that synthetic
horizontal branch models, consistent with the complex star formation
history of a galaxy, are calculated and matched to the observations.

The synthetic HB (and RGB) modelling allows to address the issue of the
possible presence of He-enhanced populations in Local Group
dwarf galaxies, the mass loss law in old populations not belonging to
Galactic globulars, and - as a byproduct - the
agreement between the magnitudes of the observed and predicted RGB bump
(and AGB clump) in a galaxy with complex star formation history.