The Nature and Orbit of the Ophiuchus Stream

Understand

The Ophiuchus stream is a recently discovered stellar tidal stream in the Milky Way.

• We present high-quality spectroscopic data for 14 stream member stars obtained using the Keck and MMT telescopes.
• We confirm the stream as a fast moving ($v_{los}\sim290$ km s$^{-1}$), kinematically cold group ($\sigma_{v_{los}}\lesssim1$ km s$^{-1}$) of $\alpha$-enhanced and metal-poor stars (${\rm [\alpha/Fe]\sim0.4}$ dex, ${\rm [Fe/H]\sim-2.0}$ dex).
• Using a probabilistic technique, we model the stream simultaneously in line-of-sight velocity, color-magnitude, coordinate, and proper motion space, and so determine its distribution in 6D phase-space.