Abstract
The Pisces overdensity was discovered as an excess of RR Lyrae stars in multi-epoch data of SDSS. Located at a distance of about 85 kpc from the Sun, it is the most distant substructure in the Galactic halo known to date. In this work we study the properties of the Pisces overdensity using spectroscopic data of several RR Lyrae stars observed with the Gemini-South telescope. We find that the distribution of radial velocities in the overdensity is bimodal, suggesting that two different streams are present in that volume of the halo. The large spatial extension of both groups suggests they are unbound systems, likely debris of a tidally disrupted galaxy or galaxies. Whether both kinematic groups have the same or different progenitors is unclear.
