TY - JOUR 
A1 - Peñarrubia, J.
AU - Martínez-Delgado, D.
AU - Rix, H. W.
AU - Gómez Flechoso, María Ángeles
AU - Munn, J.
AU - Newberg, H.
AU - Grebel, E. K.
T1 - A comprehensive model for the Monoceros tidal stream 
Y1 - 2005
SN - 0004637X
UR - http://hdl.handle.net/11268/5506
AB - 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. Because of the lack of observational data in the whole range of Galactic latitudes, the
geometrical/kinematical constraints lead to a wide range of possible locations. By associating older parts of the model
stream with lower metallicity parts of the observed data, we argue in favor of a current location of l  245
,
b   18
, with a distance to the Sun rs ’ 15 kpc. The mass of the progenitor has been poorly constrained because of
the slow orbital decay. Similar fits have been obtained for masses (3 9) ; 108 M . We have analyzed the possible
common origin of the Canis Major dwarf and the Monoceros stream. The Canis Major dwarf moves on a prograde,
nearly circular orbit (e ’ 0:16) in the Milky Way disk (i ’ 4þ14
 4 deg). This orbital inclination is too low to account for
the large vertical dispersion of stream stars. However, the bimodal distribution of radial velocities in the central region
found by Martin et al. probably indicates that their selection criteria for identifying dwarf stars lead to a contamination
of background stars. In that case, the kinematical data outlined above might result in an underestimate of the orbital
inclination. Finally, the distance estimation to Canis Major dwarf is around a factor of 2 smaller than that obtained
from our model. Unfortunately, the possible identification of the Monoceros stream progenitor in Canis Major
remains unclear.
KW - Astrofísica
KW - Cosmología
KW - Astrofísica
KW - Cosmología
LA - eng
ER -