dwarf galaxy


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Related to dwarf galaxy: Andromeda, Andromeda galaxy

dwarf galaxy

A galaxy that is unusually faint either because of its very small size, its very low surface brightness, or both. Since galaxies exist in a continuous range of sizes from the giant ellipticals downward, the dividing line between average and dwarf is somewhat arbitrary. Since no spiral or S0 galaxies have been observed with total magnitudes below –16, this is often used as a convenient demarcation line. They contain only a few million stars and are very difficult to observe against foreground stars because they are almost completely transparent. Dwarf galaxies may make up the bulk of the cosmic population and occur in all morphologies except as spiral galaxies.

The dwarf irregulars (dI) are the most numerous of these galaxies, and contain a significant fraction of their mass as neutral hydrogen gas in a dark halo (see also LSB galaxies). Dwarf ellipticals (dE) are dominated by metal-poor halo stars, and their lack of gas or dust suggests that any star formation occurred a long time ago in these systems. In contrast, the gas-rich blue compact dwarf (BCD) galaxies are undergoing active star formation with sizes and spectra resembling giant H II regions. See also extragalactic H II region.

dwarf galaxy

[′dwȯrf ′gal·ik·sē]
(astronomy)
An elliptical galaxy with low mass and low luminosity, having at most a few tens of millions of stars.
References in periodicals archive ?
Something in the direction of this dwarf galaxy is emitting gamma rays.
Now a Russian-American team has added to the canon, finding the dwarf galaxy.
If you lived inside this dwarf galaxy, the night sky would dazzle with at least 1 million stars visible to the naked eye.
The globular cluster was discovered by John Herschel in 1834, but the parent dwarf galaxy was not discovered until 1938 by Harlow Shapley.
Several clusters of stars in the Milky Way came from the Sagittarius dwarf galaxy.
They suggest that the stars were actually once part of a dwarf galaxy that collided with the Milky Way.
THE Milky Way is gobbling up a dwarf galaxy trapped in its outer edge, say astronomers.
The new dwarf galaxy found by Holyhead-born Dr Jones and his team has ``merely'' tens of millions of stars.
Space expert Brian Yanny said at a meeting of the American Astronomical Society in Seattle: "The stars may be what's left of a collision between our Milky Way and a smaller, dwarf galaxy that occurred billions of years ago.
The new galaxy is of a type known as a dwarf galaxy because it is faint and small - unlike the Milky Way and Andromeda galaxies, the two local giants.
A research by the University of Utah found a supercompact, dwarf galaxy home to a supermassive black hole.
TEHRAN (FNA)- Astronomers discovered that an ultracompact dwarf galaxy harbors a supermassive black hole -- the smallest galaxy known to contain such a massive light-sucking object.