Discovery of the Host Cluster for the Fundamental Cepheid Calibrator Zeta Geminorum
Abstract
New and existing CORAVEL, UBVJHKs , HST, HIP/Tycho, ARO, KPNO, and DAO observations imply that the fundamental Cepheid calibrator ζ Gem is a cluster member. The following parameters were inferred for ζ 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 τ = 7.85 ± 0.15, and d = 355 ± 15 pc. The mean distance to ζ Gem from cluster membership and six recent estimates (e.g., IRSB) is d=363+/- 9(\sigma _{\bar{x}}) +/- 26 (\sigma) pc. The results presented here support the color-excess and HST parallax derived for the Cepheid by Benedict et al. 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.
- Publication:
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The Astrophysical Journal
- Pub Date:
- March 2012
- DOI:
- 10.1088/2041-8205/748/1/L9
- arXiv:
- arXiv:1202.2363
- Bibcode:
- 2012ApJ...748L...9M
- Keywords:
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- Hertzsprung-Russell and C-M diagrams;
- open clusters and associations: general;
- stars: distances;
- stars: variables: Cepheids;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- To appear in ApJ Letters