Kinematic evidence for an old stellar halo in the Large Magellanic Cloud |
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Authors: | Minniti Dante Borissova Jura Rejkuba Marina Alves David R Cook Kem H Freeman Kenneth C |
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Institution: | Department of Astronomy, Pontificia Universidad Católica, Ave?ida Vicu?a Mackenna 4860, Casilla 306, Santiago 22, Chile. dante@astro.puc.cl |
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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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