Scalelength of disc galaxies
  We have derived disk scale lengths for 30374 non-interacting disk galaxies in
all five SDSS bands. Virtual Observatory methods and tools were used to define,
retrieve, and analyse the images for this unprecedentedly large sample
classified as disk/spiral galaxies in the LEDA catalogue. Cross correlation of
the SDSS sample with the LEDA catalogue allowed us to investigate the variation
of the scale lengths for different types of disk/spiral galaxies. We further
investigat asymmetry, concentration, and central velocity dispersion as
indicators of morphological type, and are able to assess how the scale length
varies with respect to galaxy type. We note however, that the concentration and
asymmetry parameters have to be used with caution when investigating type
dependence of structural parameters in galaxies. Here, we present the scale
length derivation method and numerous tests that we have carried out to
investigate the reliability of our results. The average r-band disk scale
length is 3.79 kpc, with an RMS dispersion of 2.05 kpc, and this is a typical
value irrespective of passband and galaxy morphology, concentration, and
asymmetry. The derived scale lengths presented here are representative for a
typical galaxy mass of $10^{10.8\pm 0.54} \rm{M}_\odot$, and the RMS dispersion
is larger for more massive galaxies. Distributions and typical trends of scale
lengths have also been derived in all the other SDSS bands with linear
relations that indicate the relation that connect scale lengths in one passband
to another. Such transformations could be used to test the results of
forthcoming cosmological simulations of galaxy formation and evolution of the
Hubble sequence.
