The LMC distance modulus from Hipparcos RR-Lyrae and classical Cepheid data

Abstract

The LM method \cite{luri96}, designed to exploit the Hipparcos data to obtain luminosity calibrations, is applied to derive luminosity calibrations for RR Lyrae and classical Cepheids. From these calibrations the distance to the Large Magellanic Cloud (LMC) is estimated. The distance moduli provided by the two calibrations are in good agreement, giving a value of ~ 18.3(m) , while several previous calibrations using Hipparcos data provided inconsistent results between both types of stars. This result suggest that the Hubble constant should have a value of H_0 ~ 79 km s(-1) Mpc(-1) .