RR Lyraes and Type II Cepheids in the Magellanic Clouds: Distance Scales and Population Gradients

TL;DR

This study examines the luminosity calibration of RR Lyrae and Type II Cepheids in the Magellanic Clouds, exploring their distance scales, metallicity effects, and population gradients to improve cosmic distance measurements.

Contribution

It provides new insights into the metallicity effect on Cepheid distance scales and suggests a shared K-log(P) relation for RR Lyrae and Type II Cepheids.

Findings

Estimated metallicity effect on Cepheid PL relation: 0.29±0.11 mag/dex

Shared K-log(P) relation for RR Lyrae and Type II Cepheids

Evidence of metallicity and age gradients in the LMC

Abstract

This paper discusses the current uncertainties in luminosity calibration of the RR Lyrae variables. The difference in distance moduli between the SMC and LMC as derived from RR Lyrae stars and classical Cepheids is used to estimate a metallicity effect on the Cepheid PL(VI) relation of 0.29+-0.11 mag/dex. There is evidence that suggests RR Lyrae variables and type II Cepheids share a common K-log(P) relation. Metallicity and age gradients in the LMC are discussed from data on RR Lyrae variables and AGB stars.