Part of speech:
A system developed by Edwin Hubble in 1936 that classifies galaxies as elliptical, spiral, barred spiral, lenticular, and irregular. Hubble speculated that galaxies might fit into an evolutionary sequence from earlier elliptical galaxies to later spiral forms, but most astronomers no longer believe this is the case. Our galaxy, the Milky Way, is a spiral galaxy.
A galaxy having a central bulge surrounded by a flattened disk with no pattern of spiral arms. Lenticular galaxies are intermediate in the Hubble classification system between elliptical and spiral forms and are classified using the designation S0, or SB0 if they have a bar of stars, gas, and dust through the nucleus. Like spiral galaxies, they are disk-shaped with a central bulge, but like elliptical galaxies they contain relatively little gas and dust.
A galaxy consisting of a rotating flattened disk with an ellipsoidal central bulge from which extend a pattern of two or more luminous spiral arms. Spiral galaxies range from large bulges with tightly wound arms (classified as Sa) to small bulges with loosely wound arms (classified as Sc and in some cases Sd). The majority of the mass of a spiral galaxy is contained in its bulge, made up mostly of old stars, while the arms are composed mostly of younger stars and large amounts of interstellar gas and dust. A spherical, relatively dust-free region known as a galactic halo surrounding a spiral galaxy may contain large amounts of dark matter. The Milky Way is a spiral galaxy. &diamf3; A spiral galaxy whose central bulge has the shape of a bar from whose ends the spiral arms emanate is called a barred spiral galaxy . About a third of spiral galaxies have this straight or lozenge-shaped bar of stars, gas, and dust extending out from the nucleus. Barred spiral galaxies are classified similarly to regular spirals, from SBa (large bulge, tightly wound arms) to SBc (smaller bulge, looser arms). Astronomers believe that some elliptical galaxies containing hints of a bar and spiral might once have been barred spiral galaxies.
Find another word for irregular-galaxy. In this page you can discover 4 synonyms, antonyms, idiomatic expressions, and related words for irregular-galaxy, like: hubble classification system, elliptical-galaxy, lenticular-galaxy and spiral-galaxy.