Published online by Cambridge University Press: 12 April 2016
Eta Carinae is at once our most notable LBV but also a doubtful LBV, because its Great Eruption observed 150 years ago was so unique. Since that event exceeded other major LBV outbursts by orders of magnitude in ejected mass and energy, we are not certain that it really was an example of S Dor, P Cyg, R127-type behavior. But even if it turns out to be a freak, η Car has provided either the original example or one of the earliest hints for several facets of the LBV phenomenon, e.g.:
-- Visual-wavelength brightening with little change in luminosity during each major mass-loss event;
-- The idea of a modified Eddington limit causing instability in a critical range of surface temperature;
-- CNO-processed surface material;
-- Bipolar structure in the ejecta.