We present a kinematic and spectroscopic analysis of 38 red giant branch stars , in 7 fields , spanning the dwarf spheroidal galaxy Andromeda XXVII and the upper segment of the North West Stream .
Both features are located in the outer halo of the Andromeda galaxy at a projected radius of 50-80 kpc , with the stream extending for \sim 3 ^ { \circ } on the sky .
Our data is obtained as part of the PAndAS survey and enables us to confirm that Andromeda XXVII ’ s heliocentric distance is 827 \pm 47 kpc 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 } kms ^ { -1 } 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 } kms ^ { -1 } .
In the upper segment of the North West Stream we measure mean values for the metallicity = -1.8 \pm 0.4 , systemic velocity = -519.4 \pm 4.0 kms ^ { -1 } and velocity dispersion = 10.0 \pm 4.0 kms ^ { -1 } .
We also detect a velocity gradient of 1.7 \pm 0.3 kms ^ { -1 } kpc ^ { -1 } on an infall trajectory towards M31 .
With a similar gradient , acting in the same direction , in the lower segment we suggest that the North West Stream is not a single structure .
As the properties of the upper segment of the North West Stream and Andromeda XXVII are consistent within 90 % confidence limits , it is likely that the two are related and plausible that Andromeda XXVII is the progenitor of this stream .