Abstract:
We have compiled an extensive data set on potential parts of the Monoceros tidal stream and performed an
exhaustive survey of dwarf galaxy semianalytic orbits in order to constrain its orbital properties. The best-fit orbits are
subsequently realized as self-consistent N-body simulations in order to reproduce the spatial and velocity distribution
of satellite debris. We find that all kinematic and geometric constraints can be fit by a single stream allowing for
multiple wraps. The orbital eccentricity and inclination of the progenitor are strongly constrained to be e ¼ 0:10
0:05 and i ¼ 25 5
. Ten new estimates of proper motions from the Sloan Digital Sky Survey clearly exclude all
retrograde orbits. Particles lost by the satellite populate two nearly concentric rings, naturally explaining the detection
of stream stars at both 6–8 kpc (Ibata et al.; Newberg et al.) and 12–18 kpc (the Tri/And stream; Rocha-Pinto et al.)
from the Sun. We have attempted to predict the present location of the Monoceros stream progenitor using different
information: (1) the kinematical and spatial distribution of detections, and (2) the different mean metallicity in the
inner and the outer rings. Becaus...