Variable stars in Local Group galaxies. VIII. A new look into the dSph galaxy Canes Venatici I

Canes Venatici I (CVnI) is a distant dwarf spheroidal galaxy (dSph) satellite of the Milky Way (MW). Recent estimates of its size and luminosity suggest that it does not belong to the ultra-faint class, but rather is similar to the classical MW dSph satellites. The aim of this work is to explore the variable stars of CVnI, as unambiguous tracers for reconstructing the evolutionary and chemical characteristics of potentially old and metal-poor systems. We analyse ground-based BVI wide-field images of CVnI covering the main body of the galaxy, out to 3 times r_h. We provide a new distance estimate based on the reddening free period-Wesenheit relation of RR Lyrae stars (RRLs). In addition, the early chemical evolution of CVnI is studied using their iron distribution, obtained by employing inverse PL relations in the I band. We have found a total of 111 variable stars. 87 are new detections, of which 82 are RRLs, one is an anomalous Cepheid (AC), one is a field star, and three were initially identified as 'peculiar'. We derived a true distance modulus of = 21.69 ± 0.05 mag (218 ± 7 kpc). We also derived a metallicity distribution of RRLs that is in substantial agreement with those derived spectroscopically from red giant branch stars (RGB) and photometrically by the star formation history (SFH). Furthermore, we analyse in detail the three newly found peculiar variable stars. We analysed various scenarios that might explain their true nature, but none of them proved sufficiently robust, so we ultimately left their classification as uncertain. $ (m - M)_o $