  We reanalyze the group of stars associated kinematically with Arcturus (Eggen
1971), and confirm that they constitute a peculiar grouping of metal-poor stars
with similar apocentric radius, common angular momentum, and distinct metal
abundance patterns. These properties are consistent with those expected for a
group of stars originating from the debris of a disrupted satellite. The
Arcturus group stands out clearly in the catalog of Beers et al. (2000) as well
as in other compilations of metal-poor stars in the solar neighborhood. Its
angular momentum appears too low to arise from dynamical perturbations induced
by the Galactic bar, and coincides with that of the kinematically-peculiar
population of stars identified above and below the Galactic plane by Gilmore,
Wyse & Norris (2002): the Arcturus group is in all likelihood the solar
neighborhood extension of such population. Further analysis is needed to
confirm our proposal that Arcturus, together with some of the brightest stars
in the night sky, may have formed beyond the confines of the Galaxy. However,
validating the extragalactic origin of the Arcturus group would lend support to
the prevalence of accretion events envisioned in hierarchical models of galaxy
formation, and would suggest that early mergers may have contributed a
substantial fraction of the old and metal-deficient stars in the Galactic disk.
