  The structural parameters of a magnitude-limited sample of 148 unbarred S0-Sb
galaxies were derived to study the correlations between bulge and disk
parameters as well as the probability distribution function (PDF) of the
intrinsic equatorial ellipticity of bulges. A new algorithm (GASP2D) was used
to perform the bidimensional bulge-disk decomposition of the J-band galaxy
images extracted from the archive of the 2MASS survey. The PDF of intrinsic
ellipticities was derived from the distribution of the observed ellipticities
of the bulges and misalignments between the the bulges and disks. About 80% of
the observed bulges are not oblate but triaxial ellipsoids. Their mean axial
ratio in the equatorial plane is <B/A>=0.85. There is not significant
dependence of their PDF on morphology, light concentration or luminosity. This
has to be explained by the different scenarios of bulge formation.

Astrophysics