A Sparse Halo with a Strange Story: Probing the Outer Stellar Halo of the Spiral Galaxy M96

Using deep Hubble Space Telescope imaging, Mihos et al. study the faint outer stellar halo of the spiral galaxy M96. They detect old red giant stars at large distances, finding a broad metallicity distribution and a relatively massive but unexpectedly metal-poor halo. This places M96 well below the usual halo mass–metallicity relation, suggesting an unusual accretion history compared to other spiral galaxies.