kahkešân-e forusorx (#)
Fr.: galaxie infrarouge
A galaxy that emits most of its energy in the infrared region of the spectrum. Such galaxies are thought to have unusually high rates of star formation and are also described as → starburst galaxies.
luminous infrared galaxy (LIRG)
kahkešân-e forusorx-e tâbân
Fr.: galaxie lumineuse en infrarouge
A galaxy that emits most of its energy in the infrared and whose infrared luminosity (in the 8-1000 µm range) is more than 1011 solar luminosities. → ultraluminous infrared galaxy.
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.