The VMC Survey -- XXXV. Model fitting of LMC Cepheid light curves

TL;DR

This study applies light curve model fitting to optical and near-infrared data of 18 LMC Cepheids, deriving distances and relations that suggest non-canonical stellar phenomena influence their properties.

Contribution

It introduces a detailed model fitting approach to LMC Cepheids using multi-filter data, providing refined distance estimates and insights into stellar physics.

Findings

LMC distance modulus estimated at 18.56 mag

Derived Period--Radius, Period--Luminosity, and Period--Wesenheit relations

Cepheids are brighter than canonical models predict

Abstract

We present the results of the light curve model fitting technique applied to optical and near-infrared photometric data for a sample of 18 Classical Cepheids (11 fundamentals and 7 first overtones) in the Large Magellanic Cloud (LMC). We use optical photometry from the OGLE III database and near--infrared photometry obtained by the European Southern bservatory public survey "VISTA near--infrared survey of the Magellanic Clouds system". Iso--periodic nonlinear convective model sequences have been computed for each selected Cepheid in order to reproduce the multi--filter light curve amplitudes and shape details. The inferred individual distances provide an intrinsic weighted mean value for the LMC distance modulus of $\mu_0=18.56$ mag with a standard deviation of 0.13 mag. We derive also the Period--Radius, the Period--Luminosity and the Period--Wesenheit relations that are consistent with similar relations in the literature. The intrinsic masses and luminosities of the best--fitting models show that all the investigated pulsators are brighter than the redictions of the canonical evolutionary mass--luminosity relation, suggesting a significant efficiency of non--canonical phenomena, such as overshooting, mass loss and/or rotation.