Homogeneous Stellar Parameters as the Foundation of Exoplanet Demographics

Understanding exoplanet populations requires stellar parameters that are not only precise but alsohomogeneous across surveys and methods. Differences in spectroscopic pipelines, line lists, and modelingassumptions imprint systematic offsets on Teff, log g, [Fe/H], and detailed abundances, which then propagateinto planet radii, masses, densities, and inferred compositions. Recent inter-comparisons of high-quality datasetsand instruments show that methodological choices alone can shift stellar solutions, underscoring the need forunified approaches in demographic studies (Adibekyan, 2020, A&A).I will show how the latest SWEET-Cat release built on a homogeneous EW analysis with ARES+MOOGexpanded the pool of uniformly characterized FGK hosts and enabled refreshed tests of the mass-radius planeand metallicity-linked phenomena with improved internal consistency (Sousa et al., 2024, A&A 691). I willalso illustrate how combining Gaia data with homogeneous stellar parameters allows one to obtain equallyhomogeneous planetary properties, ensuring that planet radii, masses, and derived bulk compositions rest on aconsistent stellar foundation.I will then outline several use cases where homogeneous chemical abundances add diagnostic power: forexample interpreting the separation between rocky and volatile-rich regimes inthe mass-radius diagram (e.g. Otegi et al., 2020, A&A). For these types of studies, resources like the HypatiaCatalog (Hinkel et al., 2014, AJ; Hypatia Catalog website) remain valuable, but because they compilemany heterogeneous literature sources, they inevitably encode method-to-method systematics unless furtherhomogenization steps are applied.Taken together, these results show that homogeneity is not a luxury: it is a requirement for establishing reliabletrends in occurrence rates, the mass-radius plane, and radius inflation. I will close by suggesting a practicalroadmap (shared pipelines, cross-calibration, and publicly maintained, regularly updated releases) to ensurethat stellar and chemical baselines no longer limit the fidelity of exoplanet demographics.