The influence of metallicity on the Leavitt Law from geometrical distances of Milky Way and Magellanic Clouds Cepheids

Understand

The Cepheid Period-Luminosity (PL) relation is the key tool for measuring astronomical distances and for establishing the extragalactic distance scale.

• In particular, the local value of the Hubble constant ($H_0$) strongly depends on Cepheid distance measurements.
• The recent Gaia Data Releases and other parallax measurements from the Hubble Space Telescope (HST) already enabled to improve the accuracy of the slope ($\alpha$) and intercept ($\beta$) of the PL relation.
• However, the dependence of this law on metallicity is still largely debated.