The VMC survey – XXXV. model fitting of LMC Cepheid light curves

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 Observatory 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 µ 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 predictions of the canonical evolutionary mass-luminosity relation, suggesting a significant efficiency of non-canonical phenomena, such as overshooting, mass loss and/or rotation.

An Extended Theoretical Scenario for Classical Cepheids. I. Modeling Galactic Cepheids in the Gaia Photometric System

“…However we better reproduce Molinaro et al (2012) relation at shorter periods whereas the opposite occurs with Gallenne et al (2017) relation. We finally note that the PR relations obtained by Molinaro et al (2012) and Gallenne et al (2017) depend on the assumed projection-factor (p-factor) value 5 , while those derived by the models do not depend on this parameter (Ragosta et al 2019) . Therefore a comparison between these two independent derivations allows us to put constraints on the value of the p-factor (e.g.…”

New insights into the use of Ultra Long Period Cepheids as cosmological standard candles

“…Among these 3 ULPs, 8-1498 and H42 present inconsistency between their position in the CMD and the measured periods, thus suggesting that further observations are needed to confirm their nature as ULP. As for 8-0326, we apply the theoretical light-curve model fitting method, by using new ad hoc pulsation models based on a non linear, non local, time-dependent convective code (Natale et al 2008;Marconi et al 2013a;Ragosta et al 2019). Through a 2 analysis of an extended set of models with the period fixed to the observed value and a wide range of input parameters, we were able to constrain the intrinsic stellar properties and constrain both the individual distance modulus and absorption.…”

“…Wesenheit relation is discussed in Section 3 and the other ULP properties are analyzed in section 4. In Section 5 we discuss the comparison of the ULP sample with theoretical pulsational models, analysing, in particular, the properties of the M31 ULPs, for which time-series data are available (Ngeow et al 2015;Taneva et al 2020), and the light curve model fitting technique can be applied (see also Marconi et al 2013aMarconi et al , 2017Ragosta et al 2019, and references therein). The Conclusions close the paper.…”

O experimento “curva de luz” do Laboratório Remoto de Física: uma proposta de atividade investigativa contextualizada epistemologicamente

“…A função adotada para descrever o comportamento da potência da lâmpada é uma variação de funções tipicamente empregadas em ajustes com curvas de luz de estrelas variáveis Cefeidas clássicas [35][36][37]. Tendo em consideração os objetivos pedagógicos do experimento em questão, entretanto, optou-se por uma versão simplificada (k = 4) das equações, mas que é adequada tanto para produzir uma simulação verossímil do fenômeno, quanto permitir ter uma noção das técnicas que são aplicadas nos ajustes.…”