The inner halo of M 87: a first direct view of the red-giant population
The inner halo of M 87: a first direct view of the red-giant population
An unusually deep (V,I) imaging dataset for the Virgo supergiant M87 with the Hubble Space Telescope ACS successfully resolves its brightest red-giant stars, reaching M_I(lim) = -2.5. After assessing the photometric completeness and biasses, we use this material to estimate the metallicity distribution for the inner halo of M87, finding …