Tracing the structure of the Perseus arm with IPHAS

Research aiming to describe the spiral structure of the Milky Way disc has to confront both difficulties in obtaining distances and the high interstellar extinction found in the Galactic plane. We present a study of a section of the Perseus Arm, between Galactic longitudes. (120°, 140°) and Galactic latitudes .(-1°+4°), including a number of young clusters. Determination of physical parameters of young stellar objects (YSO) and mapping of the A-star surface density are used to analyse evidence of young structures (typically 10-100 Myrs old) defined in space