The Red Sequence at Birth in the Galaxy Cluster Cl J1449+0856 at z = 2
V. Strazzullo et al 2016 ApJL 833 L20
HST images of the low-mass cluster Cl J1449+0856, likely a typical progenitor of an average massive cluster today, show a red population in the core that is a mixture of quiescent and dusty star-forming galaxies.