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dwarf spheroidal galaxy

(dSph, dwarf spheroidal, spheroidal)
(spheroidally-shaped dwarf galaxy lacking star formation)

The term dwarf spheroidal galaxy is used for some dwarf galaxies in the Local Group that have a somewhat spherical shape, a low luminosity, and little gas, dust, or star formation. Examples:

Dwarf spheroidal galaxies (or at least some of them) have shown velocity dispersions indicating a larger ratio of dark matter to gas/stars than typical (DM-dominated dwarf spheroidals). Explaining this has motivated research: it is presumed that galaxies form over regions of high DM density, so models are developed that would make less stars and gas form, or cause the galaxy to lose some, and other explanations make suggestions about the nature of dark matter itself.


(galaxy type)
Further reading:
http://en.wikipedia.org/wiki/Dwarf_spheroidal_galaxy

Referenced by pages:
dwarf galaxy classification
galaxy
Sagittarius Dwarf Elliptical Galaxy (Sgr dE)

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