Cepheid Metallicity in the Leavitt Law (C-MetaLL) survey: X First spectroscopic characterization of Galactic Type II Cepheids and calibration of the Period-Wesenheit-Metallicity relations

T. Sicignano, M. Romaniello, A. Bhardwaj +13

Type II Cepheids (T2Cs) are Population II pulsating stars that serve as distance indicators through their period--luminosity relation. Along with RR Lyrae stars and the tip of the…