"Classical Cepheid Pulsation Models from Gaia to JWST: Implications for the Distance Scale and Stellar Population Studies"
ESO Lunch Talk
- Date: Apr 14, 2026
- Time: 12:00 PM - 12:45 PM (Local Time Germany)
- Speaker: Giulia De Somma (INAF-Naples)
- Location: ESO
- Room: Auditorium Telescopium (ESO HQE, Garching)
Abstract:
Classical Cepheids are fundamental calibrators of the cosmic distance scale and powerful tracers of stellar populations. In this talk, I present a new grid of nonlinear, convective pulsation models computed with the Stellingwerf hydrodynamical code.
The models are computed by simultaneously varying the mass–luminosity relation and the efficiency of superadiabatic convection, enabling a systematic exploration of key physical uncertainties. In the Gaia passbands, they provide the first homogeneous theoretical atlas of light curves, together with new metallicity-dependent Period–Luminosity–Color and Period–Wesenheitrelations. When applied to Galactic Cepheids with measured metallicities, these relations allow the derivation of theoretical parallaxes that can be directly compared with Gaia astrometry, offering an independent assessment of the Gaia parallax zero-point in view of Gaia DR4.
The same framework is extended to the near-infrared by transforming bolometric light curves into the JWST and Roman photometric systems. I will briefly present the first theoretical Period–Luminosity–Color and Period–Wesenheit relations in these bands, currently in preparation, along with initial predictions for the distance scale and a comparison with recent results based on JWST Cepheid samples from the literature.
By combining pulsation models with updated BaSTI evolutionary tracks, new metallicity-dependent Period–Age and Period–Age–Color relations are also derived in both Gaia and JWST passbands, enabling precise age estimates for Galactic Cepheids and providing new constraints on the recent star-formation history of nearby galaxies.
These results define a unified theoretical framework bridging Gaia, JWST, and Roman observations, providing essential tools for next-generation high-precision measurements of the Hubble constant and for the study of stellar populations in the Local Universe. Implications for ongoing efforts within the SPECTRUM project will also be briefly discussed.
Classical Cepheids are fundamental calibrators of the cosmic distance scale and powerful tracers of stellar populations. In this talk, I present a new grid of nonlinear, convective pulsation models computed with the Stellingwerf hydrodynamical code.
The models are computed by simultaneously varying the mass–luminosity relation and the efficiency of superadiabatic convection, enabling a systematic exploration of key physical uncertainties. In the Gaia passbands, they provide the first homogeneous theoretical atlas of light curves, together with new metallicity-dependent Period–Luminosity–Color and Period–Wesenheitrelations. When applied to Galactic Cepheids with measured metallicities, these relations allow the derivation of theoretical parallaxes that can be directly compared with Gaia astrometry, offering an independent assessment of the Gaia parallax zero-point in view of Gaia DR4.
The same framework is extended to the near-infrared by transforming bolometric light curves into the JWST and Roman photometric systems. I will briefly present the first theoretical Period–Luminosity–Color and Period–Wesenheit relations in these bands, currently in preparation, along with initial predictions for the distance scale and a comparison with recent results based on JWST Cepheid samples from the literature.
By combining pulsation models with updated BaSTI evolutionary tracks, new metallicity-dependent Period–Age and Period–Age–Color relations are also derived in both Gaia and JWST passbands, enabling precise age estimates for Galactic Cepheids and providing new constraints on the recent star-formation history of nearby galaxies.
These results define a unified theoretical framework bridging Gaia, JWST, and Roman observations, providing essential tools for next-generation high-precision measurements of the Hubble constant and for the study of stellar populations in the Local Universe. Implications for ongoing efforts within the SPECTRUM project will also be briefly discussed.