3C 17: The BCG of a galaxy cluster at z=0.22
  Gemini Multi Object Spectrograph medium-resolution spectra and photometric
data of 39 objects in the field of the radio galaxy 3C 17 are presented. Based
on the new data, a previously uncataloged cluster of galaxies is identified at
a mean redshift of z=0.220 +/-0.003, a projected virial radius of 0.37 Mpc, and
a velocity dispersion of sigma_v = 821 +/-171 km/s. The brightest member of
this cluster is 3C 17 with M_r = -22.45 mag. The surface brightness profile of
3C 17 is best fit with two components (Exponential + Sersic) characteristic of
brightest cluster galaxies. The spectrum of 3C 17 is dominated by broad
emission lines Halpha + N[II] and Hbeta + [OIII]. Analysis of Chandra data
shows extended emission around the cluster core that supports the existence of
hot gas cospatial with 3C 17. The discovery of a cluster of galaxies around 3C
17 better explains the sharply bent morphology of the radio jet given that it
propagates through a dense intracluster medium.
