On the Discrepancy between the Cepheid and RR Lyrae Distance Scales

Abstract

view Abstract Citations (35) References (51) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Discrepancy between the Cepheid and RR Lyrae Distance Scales van den Bergh, Sidney Abstract Available evidence suggests that there is a small discrepancy between distances to Local Group dwarf galaxies determined from Cepheids and RR Lyrae stars. This difference might be due to a slight metallicity dependence of the period luminosity relation for classical Cepheids. Such a dependence would have to be in the sense that metal-poor Cepheids of a given period are slightly fainter than their metal-rich counterparts. If this hypothesis is correct then recent Hubble Space Telescope distances to IC 4182 (SN 1937C) and NGC 5253 (SN 1972E) may have been slightly overestimated, resulting in a small increase in the Hubble parameter H0. Alternatively, the adopted relation between the metallicity and luminosity of RR Lyrae variables might be in error. It is noted that the rather faint Mv(RR) values observed in giant galaxies appear to conflict with the brighter values predicted by horizontal branch models. Publication: The Astrophysical Journal Pub Date: June 1995 DOI: 10.1086/175763 Bibcode: 1995ApJ...446...39V Keywords: COSMOLOGY: DISTANCE SCALE; GALAXIES: DISTANCES AND REDSHIFTS; GALAXIES: LOCAL GROUP; STARS: ABUNDANCES; STARS: VARIABLES: CEPHEIDS full text sources ADS | data products SIMBAD (18) NED (8)