The Great Eruption of η Carinae

Arising from A. Rest et al. Nature 482, 375–378 (2012).10.1038/nature10775 During the years 1838–1858, the very massive star η Carinae became the prototype supernova impostor: it released nearly as much light as a supernova explosion and shed an impressive amount of mass, but survived as a star1. In the standard interpretation, mass was driven outward by excess radiation pressure, persisting for several years. From a light-echo spectrum of that event, Rest et al.2 conclude that “other physical mechanisms” are required to explain it, because the gas outflow appears cooler than theoretical expectations. Here we note that (1) theory predicted a substantially lower temperature than they quoted, and (2) their inferred observational value is quite uncertain. Therefore, analyses so far do not reveal any significant contradiction between the observed spectrum and most previous discussions of the Great Eruption and its physics.