Abstract

"Spectroscopic observations have been obtained of eighteen RR Lyrae stars (RRLs) belonging to the ""12.4 hr clump"", a prominent halo overdensity in the QUEST RRLs survey. Ten blue horizontal branch stars in the same region of space that had been measured by Sirko et al. (2004) were added to this sample. Thirteen of the 28 stars in the whole sample have very similar radial velocities, which is strong evidence that they constitute a stellar stream. Measurements of [Fe/H] for seven of the RRLs in the stream indicate that in the mean it is very metal poor, but with significant star to star variations in metallicity. This suggests that the stream, which is located in Virgo, is debris from the tidal destruction of a low luminosity dwarf galaxy. © 2006: Instituto de Astronomía."