Quantitative measure of evolution of bright cluster galaxies at moderate
  redshifts
  Using archival data from the Hubble Space Telescope, we study the
quantitative morphological evolution of spectroscopically confirmed bright
galaxies in the core regions of nine clusters ranging in redshift from $z =
0.31$ to $z = 0.84$. We use morphological parameters derived from two
dimensional bulge-disk decomposition to study the evolution. We find an
increase in the mean bulge-to-total luminosity ratio $B/T$ as the Universe
evolves. We also find a corresponding increase in the fraction of early type
galaxies and in the mean S\'ersic index. We discuss these results and their
implications to physical mechanisms for evolution of galaxy morphology.
