000007669 001__ 7669
000007669 005__ 20251227102916.0
000007669 037__ $$aSCART-2025-0160
000007669 100__ $$aBreuval, L.
000007669 245__ $$aConverging on the Cepheid Metallicity Dependence: Implications of Non-Standard Gaia Parallax Recalibration on Distance Measures
000007669 260__ $$c2025
000007669 520__ $$aBy comparing Cepheid brightnesses with geometric distance measures including Gaia EDR3 parallaxes, most recent analyses conclude metal-rich Cepheids are brighter, quantified as γ ∼ −0.2 mag dex−1. While the value of γ has little impact on the determination of the Hubble constant in contemporary distance ladders (due to the similarity of metallicity across these ladders), γ plays a role in gauging the distances to metal-poor dwarf galaxies like the Magellanic Clouds and is of considerable interest in testing stellar models. Recently, B. F. Madore & W. L. Freedman (hereafter MF25) recalibrated Gaia EDR3 parallaxes by adding to them a magnitude offset to match certain historic Cepheid parallaxes, which otherwise differ by ∼1.6σ. A calibration that adjusts Gaia parallaxes by applying a magnitude offset (i.e., a multiplicative correction in parallax) differs significantly from the Gaia Team’s calibration, which is additive in parallax space—especially at distances much closer than 1 kpc or beyond 10 kpc, outside the ∼2–3 kpc range on which the MF25 calibration was based. The MF25 approach reduces γ to zero. If broadly applied, it places nearby cluster distances like the Pleiades too close compared to independent measurements, while leaving distant quasars with negative parallaxes. We conclude that the MF25 proposal for Gaia calibration and γ ∼ 0 produces farther-reaching consequences, many of which are strongly disfavored by the data.
000007669 594__ $$aNO
000007669 6531_ $$aCepheid variable stars
000007669 6531_ $$aDistance measure
000007669 6531_ $$aParallax
000007669 6531_ $$aMetallicity 
000007669 700__ $$aAnand, G.S. 
000007669 700__ $$aAnderson, R.I.
000007669 700__ $$aBeaton, R. 
000007669 700__ $$aBhardwaj, A.
000007669 700__ $$aCasertano, S.
000007669 700__ $$aClementini, G.
000007669 700__ $$aCruz Reyes, M.
000007669 700__ $$aDe Somma, G.
000007669 700__ $$aGroenewegen, M.A.T. 
000007669 700__ $$aHuang, C.D.
000007669 700__ $$aKervella, P.
000007669 700__ $$aKhan, S.
000007669 700__ $$aMacri, L.M. 
000007669 700__ $$aMarconi, M. 
000007669 700__ $$aMinniti, J.H.
000007669 700__ $$aRiess, A.G.,
000007669 700__ $$aRipepi, V.,
000007669 700__ $$aRomaniello, M.,
000007669 700__ $$aScolnic, D.
000007669 773__ $$c111$$pastrophysical journal$$v994$$y2025
000007669 8560_ $$fmartin.groenewegen@ksb-orb.be
000007669 8564_ $$s2921102$$uhttp://publi2-as.oma.be/record/7669/files/BreuvalAnand_2025ApJ994_111_metallicitydependence_PLrelation.pdf
000007669 8564_ $$s24254$$uhttp://publi2-as.oma.be/record/7669/files/BreuvalAnand_2025ApJ994_111_metallicitydependence_PLrelation.jpg?subformat=icon-180$$xicon-180
000007669 8564_ $$s9627$$uhttp://publi2-as.oma.be/record/7669/files/BreuvalAnand_2025ApJ994_111_metallicitydependence_PLrelation.gif?subformat=icon$$xicon
000007669 905__ $$apublished in
000007669 980__ $$aREFERD