Astrophys. J., 741, L36 (2011/November-2)
Concerning the classical cepheid VIC Wesenheit function's strong metallicity dependence.
MAJAESS D., TURNER D. and GIEREN W.
Abstract (from CDS):
Evidence is presented which supports findings that the classical Cepheid VIC period Wesenheit function is relatively insensitive to metallicity. The viability of a recently advocated strong metallicity dependence was evaluated by applying the proposed correction (γ = -0.8 mag/dex) to distances established for the Magellanic Clouds via a Galactic VIC Wesenheit calibration, which is anchored to 10 nearby classical Cepheids with measured Hubble Space Telescope (HST) parallaxes. The resulting γ-corrected distances for the Magellanic Clouds (e.g., Small Magellanic Cloud, µ_0, γ_∼ 18.3) are in significant disagreement with that established from a mean of >300 published estimates (NED-D), and a universal Wesenheit template featuring 11 δ Scuti, SX Phe, RR Lyrae, and Type II Cepheid variables with HST/Hipparcos parallaxes. Conversely, adopting a null correction (i.e., γ = 0 mag/dex) consolidates the estimates. In tandem with existing evidence, the results imply that variations in chemical composition among Cepheids are a comparatively negligible source of uncertainty for-based extragalactic distances and determinations of H0. A new approach is described which aims to provide additional Galactic Cepheid calibrators to facilitate subsequent assessments of the VIC Wesenheit function's relative (in) sensitivity to abundance changes. VVV/UKIDSS/Two Micron All Sky Survey JHKs photometry for clusters in spiral arms shall be employed to establish a precise galactic longitude-distance relation, which can be applied in certain cases to determine the absolute Wesenheit magnitudes for younger Cepheids.
distance scale - galaxies: distances and redshifts - stars: variables: Cepheids
IC 4128 is a misprint for IC 4182.
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