Fig 7 - uploaded by Gerry Gilmore
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The luminosity function of the UMi dSph galaxy, and that of two old metal-poor globular clusters (M15, M92). The similarity shows that the stellar IMF is not a function of environment. (from Wyse etal 2002.)
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Stellar Populations are the fossil record of Galactic evolution. Interpretation of this record in the Local Group allows one to determine reliably the dominant physics controlling the evolution of those galaxies which are typical of the luminosity in the Universe, and is an essential prerequisite to understanding necessarily limited data at high re...
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... results of Wyse etal are shown in figure 7. The main-sequence stellar luminosity function of the Ursa Minor dSph, and the implied IMF down to ∼ 0.3 M ⊙ , is indistinguishable from that of the halo globular clusters M92 and M15, systems with the same old age and low metallicity as the stars in the Ursa Minor dSph. ...
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The thick disk of the Milky Way Galaxy is of great importance to study structure and evolution of our Galaxy and external galaxies as well. The history of the researches on the Galactic structure and the processes to find the thick disk are briefly received. The current well-known properties of the thick disk are summarized. Possible mechanisms for the formation of the thick disk, including gravitational collapse, satellite mergers, direct accretion and kinematic diffusion, are presented and discussed in detail. It seems that mergers of satellite galaxies should be the most likely mechanism several giga years ago.
Distances to galaxies in the Local Group are reviewed. In particular, the
distance to the Large Magellanic Cloud is found to be $(m-M)_0 = 18.52 \pm
0.10$, corresponding to $50,600 \pm 2,400$ pc. The importance of M31 as an
analog of the galaxies observed at greater distances is stressed, while the
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Group galaxies allows critical evaluation of the calibrations of the various
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Recent advances in the determination of stellar abundances and their impact on the study of nucleosynthesis and the chemical evolution of galaxies are discussed. It is argued that detailed interpretation of the abundance patterns among chemical elements found at different metallicities still requires solid spectroscopic data. Despite current improvements in abundance analyses, these are not, however, free from systematic errors which can hide the real history of the chemical evolution. Some examples are discussed.
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