Discovery of the Host Cluster for the Fundamental Cepheid Calibrator
  Zeta Gem
  New and existing CORAVEL, UBVJHKs, HST, HIP/Tycho, ARO, KPNO, and DAO
observations imply that the fundamental Cepheid calibrator Zeta Gem is a
cluster member. The following parameters were inferred for Zeta Gem from
cluster membership and are tied to new spectral classifications (DAO)
established for 26 nearby stars (e.g., HD53588/B7.5IV, HD54692/B9.5IV):
E(B-V)=0.02+-0.02, log t=7.85+-0.15, and d=355+-15 pc. The mean distance to
Zeta Gem from cluster membership and six recent estimates (e.g., IRSB) is
d=363+-9(se)+-26(sd) pc. The results presented here support the color-excess
and HST parallax derived for the Cepheid by Benedict et al. (2007). Forthcoming
precise proper motions (DASCH) and Chandra/XMM-Newton observations of the
broader field may be employed to identify cluster members, bolster the
cluster's existence, and provide stronger constraints on the Cepheid's
fundamental parameters.
