IATE   20350
INSTITUTO DE ASTRONOMIA TEORICA Y EXPERIMENTAL
Unidad Ejecutora - UE
artículos
Título:
A Sagittarius-induced origin for the Monoceros ring
Autor/es:
LEO MICHEL-DANSAC, MARIO G. ABADI, JULIO F. NAVARRO, MATTHIAS STEINMETZ
Revista:
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2011 vol. 414 p. 1 - 5
ISSN:
0035-8711
Resumen:
The Monoceros ring is a collection of stars in nearly circular orbits at
roughly 18 kpc from the Galactic Centre. It may have originated (i) as
the response of the disc to perturbations excited by satellite
companions or (ii) from the tidal debris of a disrupted dwarf galaxy.
The metallicity of Monoceros stars differs from that of disc stars at
comparable Galactocentric distances, an observation that disfavours the
first scenario. On the other hand, circular orbits are difficult to
accommodate in the tidal-disruption scenario, since it requires a
satellite which at the time of disruption was itself in a nearly
circular orbit. Such satellite could not have formed at the location of
the ring and, given its low mass, dynamical friction is unlikely to have
played a major role in its orbital evolution. We search cosmological
simulations for low-mass satellites in nearly circular orbits and find
that they result, almost invariably, from orbital changes induced by
collisions with more massive satellites: the radius of the circular
orbit thus traces the galactocentric distance of the collision.
Interestingly, the Sagittarius dwarf, one of the most luminous
satellites of the Milky Way, is in a polar orbit that crosses the
Galactic plane at roughly the same Galactocentric distance as Monoceros.
We use idealized simulations to demonstrate that an encounter with
Sagittarius might well have led to the circularization and subsequent
tidal demise of the progenitor of the Monoceros ring.