First Results From the Large Binocular Telescope: Deep Photometry of New dSphs

Abstract

This contribution describes photometry for two Galactic dSphs obtained with the Large Binocular Telescope to a magnitude of ~25.5. Using the Large Binocular Camera, a purpose-built wide-field imager for the LBT, we have examined the structure and star formation histories of two newly-discovered Local Group members, the Hercules dSph and the Leo T dSph/dIrr system. We have constructed a structural map for the Hercules system using three-filter photometry to V ~ 25.5. This is the first deep photometry for this system, and it indicates that Hercules is unusually elongated, possibly indicating distortion due to the Galactic tidal field. We have also derived the first star formation history for the Leo T system, and find that its oldest population of stars (age ~ 13 Gyr) were relatively metal-rich, with [Fe/H] ~ -1.5.