Kinematic evidence for an old stellar halo in the Large Magellanic Cloud.
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.
Minniti
Dante
D
Department of Astronomy, Pontificia Universidad Católica, Aveñida Vicuña Mackenna 4860, Casilla 306, Santiago 22, Chile. dante@astro.puc.cl
Borissova
Jura
J
Rejkuba
Marina
M
Alves
David R
DR
Cook
Kem H
KH
Freeman
Kenneth C
KC