ultra-luminous infrared galaxy (ULIRG)
A galaxy that emits most of its total energy output in the
far (long-wavelength) infrared –
a sure sign that it contains a huge amount of dust.
Such large dust concentrations, in turn, suggest that ULIRGs are the scene
of prodigious star formation. Although
ULIRGs are still found in the universe today, recent surveys suggest they
were much more common in the remote past and contribute significantly to
the cosmic background in the far-infrared and submillimeter bands.
|Color composite image of ultra-luminous infrared
galaxy IRAS 19297-0406 made by the Hubble Space Telescope