Type II and Anomalous Cepheids as Independent Distance Indicators in the Local Universe

Classical Cepheids (CCs) are young, massive, pulsating stars and the primary calibrators of the distance ladder for measuring the Hubble constant in the local Universe. The broader class of Cepheids also includes Type II Cepheids (T2Cs) and Anomalous Cepheids (ACs), which are less massive, older, and common in dwarf galaxies and the Milky Way. Each Cepheid type follows a distinct Period-Luminosity (PL) and Period-Wesenheit (PW) relation, particularly tight in near-infrared bands.In the context of the current "Hubble tension", ACs and T2Cs—along with RR Lyrae stars and the tip of the red giant branch—offer an independent path to calibrating the Cosmic Distance Ladder without relying on CCs.In this work, we present new multi-wavelength PL and PW relations for T2C subclasses (BLHer, WVir, pWVir, and RVTau) and both fundamental and first overtone ACs in the Magellanic Clouds (MCs). We used optical data from the OGLE survey and Gaia mission, and near-infrared photometry from the VISTA YJKs survey of the MC system (VMC, PI M.-R.L. Cioni).We analyzed $YJK_s$ time-series for 200 ACs and over 300 T2Cs in the MCs. The resulting PL/PW relations were used to estimate distances to several Local Group stellar systems. The comparison of these distances with those from other pulsators—such as CCs and RR Lyrae stars—shows general agreement within uncertainties, reinforcing the reality of the Hubble tension, independently of the details of the traditional distance ladder.This work is being extended by including a new sample that spans a broader metallicity range. Our multi-band photometry and high-resolution spectroscopy will enable us to test the metallicity sensitivity of the PL relations.