Draco Dwarf - Dark Matter

Dark Matter

Recently, dwarf spheroidal galaxies have become key objects for the study of dark matter. The Draco Dwarf is one which has received specific attention. Radial velocity computations of Draco have revealed a large internal velocity dispersion giving a mass to luminosity ratio of up to 440 M/L, suggesting large amounts of dark matter. It has been hypothesized that large velocity dispersions could be explained as tidal dwarfs (virtually unbound stellar streams from dwarf galaxies tidally disrupted in the Milky Way potential). However, Draco Dwarf's narrow horizontal branch width does not support this model. This only leaves the dark matter explanation and makes Draco Dwarf the most dark matter dominated object known as of 2007. The dark matter distribution within Draco Dwarf is at least nearly isothermal.

At large radii, radial velocity dispersion exhibit strange behavior. One possible explanation for this would be the presence of more than one stellar population. This suggests the need for further study of Draco Dwarf population's metallicity and ages and of dwarf spheroidals in general.

Read more about this topic:  Draco Dwarf

Famous quotes containing the words dark and/or matter:

    I cannot say what poetry is; I know that our sufferings and our concentrated joy, our states of plunging far and dark and turning to come back to the world—so that the moment of intense turning seems still and universal—all are here, in a music like the music of our time, like the hero and like the anonymous forgotten; and there is an exchange here in which our lives are met, and created.
    Muriel Rukeyser (1913–1980)

    [A] Dada exhibition. Another one! What’s the matter with everyone wanting to make a museum piece out of Dada? Dada was a bomb ... can you imagine anyone, around half a century after a bomb explodes, wanting to collect the pieces, sticking it together and displaying it?
    Max Ernst (1891–1976)