We identify a new , nearby ( 0.5 \lesssim d \lesssim 10 \mathrm { kpc } ) stream in data from the RAdial Velocity Experiment ( RAVE ) .
As the majority of stars in the stream lie in the constellation of Aquarius we name it the Aquarius Stream .
We identify 15 members of the stream lying between 30 ^ { \circ } < l < 75 ^ { \circ } and -70 ^ { \circ } < b < -50 ^ { \circ } , with heliocentric line-of-sight velocities V _ { \mathrm { los } } \sim - 200 \mathrm { km s } ^ { -1 } .
The members are outliers in the radial velocity distribution , and the overdensity is statistically significant when compared to mock samples created with both the Besançon Galaxy model and newly-developed code Galaxia .
The metallicity distribution function and isochrone fit in the \log g - T _ { \mathrm { eff } } plane suggest the stream consists of a 10 \mathrm { Gyr } old population with \hbox { [ M / H ] } \sim - 1.0 .
We explore relations to other streams and substructures , finding the stream can not be identified with known structures : it is a new , nearby substructure in the Galaxy ’ s halo .
Using a simple dynamical model of a dissolving satellite galaxy we account for the localization of the stream .
We find that the stream is dynamically young and therefore likely the debris of a recently disrupted dwarf galaxy or globular cluster .
The Aquarius stream is thus a specimen of ongoing hierarchical Galaxy formation , rare for being right in the solar suburb .