SIMBAD references

2012ApJ...747..145M - Astrophys. J., 747, 145 (2012/March-2)

New evidence supporting cluster membership for the keystone calibrator delta Cephei.


Abstract (from CDS):

New and existing UBVJHKs, spectroscopic, NOMAD, Hubble Space Telescope, and revised Hipparcos observations are employed to determine properties for δ Cep and its host star cluster. The multi-faceted approach ensured that uncertainties were mitigated (σ/d ∼ 2%). The following fundamental parameters were inferred for δ Cep: E(B - V) = 0.073±0.018(σ), log τ = 7.9±0.1, and d = 272± 3(σ{bar}x) ± 5(σ)pc. The cluster exhibits a turnoff near B6 (M*/M∼ 5), and the brightest host cluster members are the supergiants ζ Cep (K1.5Ib) and δ Cep. To within the uncertainties, the two stars share common astrometric parameters (π, µα, µδ, RV ∼ -17 km/s) and are tied to bluer members via the evolutionary track implied by the cluster's UBVJHKscolor-color and color-magnitude diagrams. The cluster's existence is bolstered by the absence of an early-type sequence in color-magnitude diagrams for comparison fields. NOMAD data provided a means to identify potential cluster members (n ∼ 30) and double the existing sample. That number could increase with forthcoming precise proper motions (DASCH) for fainter main-sequence stars associated with classical Cepheids (e.g., δ Cep), which may invariably foster efforts to strengthen the Galactic Cepheid calibration and reduce uncertainties tied to H0.

Abstract Copyright:

Journal keyword(s): Hertzsprung-Russell and C-M diagrams - open clusters and associations: general - stars: distances - stars: variables: Cepheids

Simbad objects: 48

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