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galaxy
subjectfact 
galaxyhas number of stars 106 to 1012has source: Abbot, D. 1984 Astronomers, Peter Bedrick Books, New York, 2001-09-27 09:31:09.0
has catalog galaxy catalog2001-09-27 09:31:09.0
has definition Vast system of celestial objects, typically consisting of between 106 and 1012 stars, plus interstellar gas and dust. There are three basic types: spiral (further subdivided into normal spirals and spirals with a "bar" at the centre, and yet further subdivided according to the "openness" of the spiral arms), elliptical (subdivided according to ellipticity) and irregular (subdivided according to whether they are made up of Population I or Population II stars). Another not uncommon type of galaxy is a lenticular form mid-way between the spiral and the elliptical.has source: Abbot, D. 1984 Astronomers, Peter Bedrick Books, New York, 2001-09-27 09:31:09.0
has definition A huge collection of millions, billions, or trillions of stars. When referring to the Milky Way, "galaxy" is capitalized, otherwise not; thus: "Andromeda is the nearest giant galaxy to the Galaxy".has source: Croswell, K. 1995 The Alchemy of the Heavens, Anchor Books, 2001-09-27 09:31:09.0
has definition A collection of matter which usually manifests itself by the production of stars.has source: Clark, S. 1997 Towards the Edge of the Universe, Wiley, 2001-09-27 09:31:09.0
has definition A large aggregation of stars, bound together gravitationally. There are three major classifications of galaxies - spiral, elliptical, and irregular - and several subclassifications. The sun belongs to a spiral galaxy, the Milky Way galaxy.has source: Ferris, T. 1988 Coming of Age in the Milky Way, Morrow, 2001-09-27 09:31:09.0
has definition A large (108-1013 Msun), gravitationally bound aggregate of stars and interstellar matter. Galaxy formation is currently believed to have occurred around z ≈ 3-4.has source: Hopkins, J. 1976 Glossary of Astronomy and Astrophysics, University of Chicago Press, 2001-09-27 09:31:09.0
has definition An isolated aggregation of stars and gas, held together by their mutual gravity. A typical galaxy has about 100 billion stars, has a total mass equal to about a trillion times the mass of the sun, is about 100,000 light years in diameter, and is separated from the nearest galaxy by a distance of about 100 times its own diameter. Thus, galaxies are islands of stars in space. Our galaxy is called the Milky Way. Galaxies come in two major shapes: flattened disks with a central bulge, called spirals, and amorphous, semispherical blobs, called ellipticals. If galaxies are found bunched up next to each other, they are said to lie in groups or clusters. Clusters with a particularly large number of galaxies in them are called rich clusters. Galaxies that do not lie in such groups but rather seem to be scattered uniformly and randomly through space are called field galaxies. Some galaxies are characterized by the dominant type of radiation they emit.has source: Lightman, A., Brawer, R. 1990 The Lives and Worlds of Modern Cosmologists, Harvard University Press, 2001-09-27 09:31:09.0
is a kind of collection of stars2001-09-27 09:31:09.0
celestial bodyhas spectra2001-09-27 09:30:09.0
physical objecthas location or center of gravity2001-09-27 09:27:27.0
has angular momentum2001-09-27 09:27:27.0
has mass2001-09-27 09:27:27.0
has velocity2001-09-27 09:27:27.0
has momentum2001-09-27 09:27:27.0
has temperature2001-09-27 09:27:27.0
has volume2001-09-27 09:27:27.0
has extent2001-09-27 09:27:27.0
has material2001-09-27 09:27:27.0

Kinds of galaxy :

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