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ultraluminous infrared galaxy (ULIRG) kahkešân-e forusorx-e ultar-tâbân Fr.: galaxie ultralumineuse en infrarouge A galaxy that emits more than 90% of its energy in the infrared (8-1000 µm) and whose infrared luminosity exceeds 1012 solar luminosities. → luminous infrared galaxy (LIRG). Quasars can also have such high or even higher bolometric luminosities. However LIRGs and ULIRGs emit the bulk of their energy in the infrared. Most of ULIRGs are found in merging and interacting galaxy systems. It is thought that their luminosity results from galactic collisions, which increase the rate of star formation. → ultraluminous; → infrared; → galaxy. |
violent galaxy kahkašân-e surâ Fr.: galaxie violente A type of galaxy that releases a tremendous amount of energy, on the average 1058 ergs, compared with a supernova release of 1049 ergs. Violent galaxies include quasars and exploding galaxies. About 1 percent of the galaxies are classified as violent. The nearest violent galaxy is Cen A. |
weak arm spiral galaxy kahkešân-e mârpic bâ bâzu-ye nezâr Fr.: galaxie spirale à faibles bras A gas-rich galaxy that has weak stellar → spiral arms with → interarm gas and star formation more important than a typical → spiral galaxy, such as NGC 4414. |
Whirlpool galaxy (M51) kahkešân-e Gerdâb (#) Fr.: galaxie du Tourbillon A large → spiral galaxy of type Sc seen → face-on in the constellation → Canes Venatici and lying about 31 million → light-years away. Also known as M51 and NGC 5194. It is interacting with a small irregular galaxy NGC 5195. |
Wolf-Rayet galaxy kahkešân-e Wolf-Rayet Fr.: galaxie Wolf-Rayet A subset of → starburst galaxies whose integrated spectra show broad emission features attributed to the presence of hundreds to thousands → Wolf-Rayet stars. The most massive stars formed in the burst evolve rapidly into a substantial population of Wolf-Rayet stars in aggregations of ionized gas. → Wolf-Rayet star; → galaxy. |
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