Relatore
Descrizione
Classical Cepheids (DCEPs) are the primary indicators for the extra-galactic distance scale. Establishing precise zero points for their Period-Luminosity and Period-Wesenheit (PLZ/PWZ) relations is crucial for resolving the 5σ H0 tension, yet current calibrations lack statistics for low-metallicity ([Fe/H] < -0.4 dex) and long-period (P > 10 days) pulsators. While metal-poor DCEPs exist at large Galactocentric radii, they are often obscured in optical bands by dust.
GIANO-B high-resolution spectra for DCEPs at large radii or with long periods ensures a comprehensive coverage of the parameter space. By shifting the observational focus to the Near-Infrared (NIR), it is possible to mitigate interstellar extinction, reduce intrinsic scatter, and include the distant metal-poor objects necessary for a homogeneous metallicity sampling. These data, along with forthcoming Gaia DR4 parallaxes, allow to put firm constraints on the PLZ/PWZ for MW DCEPs and, in turn, provide a more stringent test of the extra-galactic distance scale. Within this framework, I will present the first preliminary results from the analysis of these infrared spectra.
| Sessione | Oggetti variabili e transienti in astrofisica |
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