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A deep view into the nucleus of the Sagittarius dwarf spheroidal galaxy: M54

Published online by Cambridge University Press:  11 March 2020

M. Alfaro-Cuello
Affiliation:
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
N. Kacharov
Affiliation:
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
N. Neumayer
Affiliation:
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
A. Mastrobuono-Battisti
Affiliation:
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
N. Lützgendorf
Affiliation:
European Space Agency, c/o STScI, 3700 San Martin Drive, Baltimore, MD21218, USA
Anil C. Seth
Affiliation:
University of Utah, Salt Lake City, UT84112, USA
T. Böker
Affiliation:
European Space Agency, c/o STScI, 3700 San Martin Drive, Baltimore, MD21218, USA
S. Kamann
Affiliation:
Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, United Kingdom
R. Leaman
Affiliation:
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
G. van de Ven
Affiliation:
University of Vienna, Türkenschanzstrasse 17, 1180 Wien, Austria
P. Bianchini
Affiliation:
Observatoire Astronomique de Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg, France
L. L. Watkins
Affiliation:
University of Vienna, Türkenschanzstrasse 17, 1180 Wien, Austria European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany email: alfaro@mpia.de
M. Lyubenova
Affiliation:
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany email: alfaro@mpia.de
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Abstract

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Nuclear star clusters hosted by dwarf galaxies exhibit similar characteristics to high-mass, metal complex globular clusters. This type of globular clusters could, therefore, be former nuclei from accreted galaxies. M54 resides in the photometric center of the Sagittarius dwarf galaxy, at a distance where resolving stars is possible. M54 offers the opportunity to study a nucleus before the stripping of their host by the tidal field effects of the Milky Way. We use a MUSE data set to perform a detailed analysis of over 6600 stars. We characterize the stars by metallicity, age, and kinematics, identifying the presence of three stellar populations: a young metal-rich (YMR), an intermediate-age metal-rich (IMR), and an old metal-poor (OMP). The evidence suggests that the OMP population is the result of accretion of globular clusters in the center of the host, while the YMR population was born in-situ in the center of the OMP population.

Keywords

Type
Contributed Papers
Copyright
© International Astronomical Union 2020

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