Bibcode
Cicuéndez, L.; Battaglia, G.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 480, Issue 1, p.251-260
Fecha de publicación:
10
2018
Número de citas
24
Número de citas referidas
21
Descripción
We report the discovery of clear observational signs of past
accretion/merger events in one of the Milky Way satellite galaxies, the
Sextans dwarf spheroidal (dSph). These were uncovered in the spatial
distribution, internal kinematics, and metallicity properties of Sextans
stars using literature CTIO/DECam photometric and Magellan/MMFS
spectroscopic catalogues. We find the spatial distribution of stars to
vary as a function of the colour/metallicity, being rather regular and
round for the blue (metal-poor) red giant branch and main-sequence
turn-off stars but much more elliptical and irregularly shaped for the
red (metal-rich) ones, with a distinct `shell-like' overdensity in the
northeast side. We also detect kinematic anomalies, in the form of a
`ring-like' feature with a considerably larger systemic line-of-sight
velocity and lower metallicity than the rest of stars; even the
photometrically selected component with a regular looking spatial
distribution displays complex kinematics. With a stellar mass of just
{˜ }5× 105 M_{⊙}, Sextans becomes the
smallest galaxy presenting clear observational signs of accretion to
date.
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