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Population II in the Milky Way Galaxy and The LMC

Published online by Cambridge University Press:  07 August 2017

Nicholas B. Suntzeff*
Affiliation:
Cerro Tololo Inter-American Observatory Casilla 603, La Serena, CHILE

Abstract

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The RR Lyrae and globular cluster populations are used to study the Pop II in the Galaxy and the LMC. The metallicity gradient in the Galaxy changes abruptly at the position of the solar circle. The statistics of field RR Lyraes imply that the Pop II field population is older towards the Galactic center. The density of RR Lyraes in the solar neighborhood implies a luminous mass density of 6.4 ± 1.8 × 10–5M pc–3 for the Galactic halo. The total luminosities (MV) for the Galactic and LMC halos are −18.4 and −15.1, and the ratio of globular cluster to luminous Pop II mass is 0.02 in both cases. The agreement of this ratio in two systems with very different tidal fields argues against the formation of the field population as the disruption of many smaller systems.

Type
I. The Stellar Populations in the Milky Way
Copyright
Copyright © Kluwer 

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