NGC 1140 is a starburst galaxy, meaning it is forming stars at a very fast rate. In fact, while it is only a tenth as wide as the Milky Way, it is producing stars at a rate of 0.65 M☉/yr,[5] about the same as the Milky Way. The image taken by the Hubble Space Telescope shows bright blue and red regions of star formation, similar to NGC 1569.[6] The starburst is estimated to have begun about 5 million years ago.[5] Its low metallicity (the ratio of hydrogen and helium to other elements) makes NGC 1140 similar to primordial galaxies.[6]
Wolf–Rayet stars, a class of blue, massive, and luminous stars, are present in this galaxy; in fact, NGC 1140 has so many of them that their spectra also appear in the galaxy's spectrum.[5] These types of galaxies are known Wolf–Rayet galaxies, and are fairly rare because Wolf–Rayet stars are a short stage in the lives of very massive stars.[7]
^ abCutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
