The light curve model fitting of LMC Cepheids: MESA-RSP versus Stellingwerf's code predictions

TL;DR

This study calibrates turbulent convection parameters in the MESA-RSP code by comparing simulated light curves of LMC Cepheids with observations and predictions from Stellingwerf's code, improving the modeling of Cepheid pulsations.

Contribution

It introduces a calibration of TC parameters in MESA-RSP using observational data and Stellingwerf models, and identifies distinct ML relations for different Cepheid modes.

Findings

Successful reproduction of multi-band light curves.

Consistent PL, PR, and PMR relations with previous studies.

Identification of separate ML relations for fundamental and overtone Cepheids.

Abstract

A major challenge in modeling classical Cepheids is the treatment of convection, particularly its complex interplay with pulsation. This inherently three-dimensional process is typically approximated in one-dimensional hydrocodes using dimensionless turbulent convection (TC) free parameters. Calibrating these parameters is essential for reproducing key observational features such as light-curve amplitudes, secondary bumps, and the red edge of the instability strip. In this work, we calibrate TC parameters adopted in the publicly available MESA-RSP code through comparison with both observational data of classical Cepheids and stellar parameter constraints from the Stellingwerf code. We compute multi-band (V, I, and Ks) MESA-RSP light curves for 18 observed Large Magellanic Cloud Cepheids, using stellar parameters determined from the Stellingwerf code. By fine-tuning the mixing-length and eddy viscosity parameters, we calibrate the TC treatment in MESA-RSP. We then compare the resulting period-luminosity (PL), period-radius (PR), and period-mass-radius (PMR) relations with predictions from the Stellingwerf models. We successfully reproduce multi-band light curves and obtain PL, PR, and PMR relations consistent with Ragosta et al. (2019). While in broad agreement with previous work, we explicitly identify distinct mass-luminosity (ML) relations for fundamental-mode and first-overtone Cepheids for the first time. This suggests that the macroscopic processes affecting the ML relation depend on stellar mass and/or effective temperature range. Although our study focuses on the calibration of TC parameters, we do not find a single set of parameter values that reproduces all light curves. No statistically significant correlation is found between stellar properties and convection parameters, although subtle trends with period and effective temperature may be present.