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Dwarf Galaxies in the Local Group

Milky Way dwarf galaxy satellites in Galactic coordinates. Blue circles are classical dwarf galaxies, and red symbols are the SDSS ultra-faint satellites (including three ultra-faint star clusters). The imaging footprint of SDSS DR8 is shown in grey (Belokurov et al. 2014). Zoom Image

Milky Way dwarf galaxy satellites in Galactic coordinates. Blue circles are classical dwarf galaxies, and red symbols are the SDSS ultra-faint satellites (including three ultra-faint star clusters). The imaging footprint of SDSS DR8 is shown in grey (Belokurov et al. 2014).

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The overwhelming majority of galaxies in the Universe are dwarf galaxies. But although they are important components in understanding galaxy evolution, these systems are typically too faint to be observed at high redshifts. However, in the Local Group we are able to obtain an unobscured view of early star formation and chemical enrichment in these galaxies.

Recently, there has been a surge in the discovery of new galaxies, coming from large photometric surveys. These numbers are expected to continue to increase over the next few years, as surveys have not yet covered the entire sky. The main advantage of studying nearby galaxies is that they provide the opportunity to resolve and study the stellar populations, star by star, either through photometry, or, in the case of the Milky Way satellites, through high-resolution spectroscopy and get detailed chemical abundances of their stellar population.

The dwarf galaxies in the Local Group have a range of properties. The resolved populations of stars of various ages, give detailed insights into the star formation histories of galaxies, as well as the chemical enrichment histories, and environmental influences. The Local Universe is the only place where the time dependent properties of single galaxies can be measured from their beginnings to the present day. These kind of studies are, therefore, directly complementary to the study of galaxies at higher redshifts, where it is possible to get large statistical samples with less detailed information available on each galaxy. 

 
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