Testing Mass Loss in Large Magellanic Cloud Cepheids using Infrared and Optical Observations II. Predictions and Tests of the OGLE-III Fundamental-Mode Cepheids

TL;DR

This study tests whether Cepheids in the Large Magellanic Cloud exhibit infrared excesses due to mass loss by fitting models to optical and infrared data, and examines implications for their Period-Luminosity relations.

Contribution

It introduces a method to estimate mass-loss rates in Cepheids using combined optical and infrared observations, and assesses their impact on P-L relations.

Findings

Predicted mass-loss rates vary from zero to 10^{-8} solar masses per year.

Infrared excesses influence the accuracy of angular diameter measurements.

The Period-Luminosity relations are non-linear at infrared wavelengths.

Abstract

In this article, we test the hypothesis that Cepheids have infrared excesses due to mass loss. We fit a model using the mass-loss rate and the stellar radius as free parameters to optical observations from the OGLE-III survey and infrared observations from the 2MASS and SAGE data sets. The sample of Cepheids have predicted minimum mass-loss rates ranging from zero to $10^{-8}M_\odot$ $yr^{-1}$, where the rates depend on the chosen dust properties. We use the predicted radii to compute the Period-Radius relation for LMC Cepheids, and to estimate the uncertainty caused by the presence of infrared excess for determining angular diameters with the infrared surface brightness technique. Finally, we calculate the linear and non-linear Period-Luminosity (P-L) relations for the LMC Cepheids at VIJHK + IRAC wavelengths and we find that the P-L relations are consistent with being non-linear at infrared wavelengths, contrary to previous results.