The nature of the Eastern Extent in the outer halo of M31
  We present the first comprehensive spectroscopic study of the Andromeda
galaxy's Eastern Extent. This ~4 degree long filamentary structure. located
70-90 kpc from the centre of M31, lies perpendicular to Andromeda's minor axis
and the Giant Stellar Stream and overlaps Stream C. In this work, we explore
the properties of the Eastern Extent to look for possible connections between
it, the Giant Stellar Stream and Stream C. We present the kinematics and
photometry for ~50 red giant branch stars in 7 fields along the Eastern Extent.
We measure the systemic velocities for these fields and find them to be -368
km/s < v < -331 km/s with a slight velocity gradient of -0.51 +/- 0.21 km/s/kpc
towards the Giant Stellar Stream. We derive the photometric metallicities for
stars in the Eastern Extent finding them to be metal-poor with values of -1.0 <
[Fe/H]phot < -0.7 with a <[Fe/H]phot> ~-0.9. We find consistent properties for
the Eastern Extent, Stream B and one of the substructures in Stream C, Stream
Cr, plausibly linking these features. Stream Cp and its associated globular
cluster, EC4, have distinctly different properties indicative of a separate
structure. When we compare the properties of the Eastern Extent to those of the
Giant Stellar Stream, we find them to be consistent, albeit slightly more
metal-poor, such that the Eastern Extent could plausibly comprise stars
stripped from the progenitor of the Giant Stellar Stream.
