The Red Giant Branch Tip and Bump of the Leo II dwarf spheroidal galaxy

We present V and I photometry of a 9.4 × 9.4 field centered on the dwarf spheroidal galaxy Leo II. The Tip of the Red Giant Branch is identified at I = 17.83± 0.03 and adopting 〈[M/H ]〉 = −1.53±0.2 from the comparison of RGB stars with Galactic templates, we obtain a distance modulus (m − M)0 = 21.84 ± 0.13, corresponding to a distance D = 233 ± 15 Kpc. Two significant bumps have been detected in the Luminosity Function of the Red Giant Branch. The fainter bump (B1, at V = 21.76± 0.05) is the RGB bump of the dominant stellar population while the actual nature of the brightest one (B2, at V = 21.35 ± 0.05) cannot be firmly assessed on the basis of the available data, it can be due to the Asymptotic Giant Branch Clump of the main population or it may be a secondary RGB bump. The luminosity of the main RGB bump (B1) suggests that the majority of RGB stars in Leo II belongs to a population that is & 4 gyr younger than the classical Galactic globular clusters. The stars belonging to the He-burning Red Clump are shown to be significantly more centrally concentrated than RR Lyrae and Blue Horizontal Branch stars, probing the existence of an age/metallicity radial gradient in this remote dwarf spheroidal.