Andromeda XXVII and the North West Stream

Both features are located in the outer halo of the Andromeda galaxy at a projected radius of 50-80kpc, with the stream extending for ~3{deg} on the sky. Our data are obtained as part of the PAndAS survey and enables us to confirm that Andromeda XXVII's heliocentric distance is 827+/-47kpc and spectroscopic metallicity is -2.1^+0.4^_-0.5_.

We also re-derive Andromeda XXVII's kinematic properties, measuring a systemic velocity =-526.1^+10.0^_-11.0_km/s and a velocity dispersion that we find to be non-Gaussian but for which we derive a formal value of 27.0^+2.2^_-3.9_km/s. In the upper segment of the North West Stream we measure mean values for the metallicity =-1.8+/-0.4, systemic velocity =-519.4+/-4.0km/s, and velocity dispersion =10.0+/-4.0km/s. We also detect a velocity gradient of 1.7+/-0.3km/s/kpc on an infall trajectory towards M31.