Stellar populations and evolution of early-type cluster galaxies:
  Constraints from optical imaging and spectroscopy of z=0.5-0.9 galaxy
  clusters
  We present an analysis of stellar populations and evolutionary history of
galaxies in three similarly rich galaxy clusters MS0451.6-0305 (z=0.54),
RXJ0152.7-1357 (z=0.83), and RXJ1226.9+3332 (z=0.89); based on high S/N
ground-based optical spectroscopy and HST imaging for 17-34 members in each
cluster. We find no indication of evolution of sizes or velocity dispersions
with redshift at a given dynamical galaxy mass. We establish the Fundamental
Plane (FP) and scaling relations between absorption line indices and velocity
dispersions. We confirm the steeper FP at z=0.86 compared to the low redshift
FP, indicating (under the assumption of passive evolution) the formation
redshift, z_form, depends on the galaxy velocity dispersion (or mass). z_form
varies from z_form=1.24+-0.05 at velocity dispersion of 125 km/s to 1.95+-0.25
at 225 km/s. The three clusters and the low redshift sample follow similar
scaling relations between absorption line indices and velocity dispersions. The
strength of the higher order Balmer lines Hdelta and Hgamma implies z_form>2.8.
From the line strengths we find that [M/H] for MS0451.6-0305 is about 0.2 dex
below that of the other clusters, and confirm our previous result that
[alpha/Fe] for RXJ0152.7-1357 is about 0.3 dex higher than that of the other
clusters. These differences between the high-redshift clusters and the low
redshift sample are inconsistent with a passive evolution scenario for
early-type cluster galaxies over the redshift interval studied. (abridged)
