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Kinematic evidence for an old stellar halo in the Large Magellanic Cloud
Authors:Minniti Dante  Borissova Jura  Rejkuba Marina  Alves David R  Cook Kem H  Freeman Kenneth C
Institution:Department of Astronomy, Pontificia Universidad Católica, Ave?ida Vicu?a Mackenna 4860, Casilla 306, Santiago 22, Chile. dante@astro.puc.cl
Abstract:The oldest and most metal-poor Milky Way stars form a kinematically hot halo, which motivates the two major formation scenarios for our galaxy: extended hierarchical accretion and rapid collapse. RR Lyrae stars are excellent tracers of old and metal-poor populations. We measured the kinematics of 43 RR Lyrae stars in the inner regions of the nearby Large Magellanic Cloud (LMC) galaxy. The velocity dispersion equals 53 +/- 10 kilometers per second, which indicates that a kinematically hot metal-poor old halo also exists in the LMC. This result suggests that our galaxy and smaller late-type galaxies such as the LMC have similar early formation histories.
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