Free Astronomy Magazine March-April 2016

36 For the first time a group of astronomers have found in neighbouring galaxies 5 objects whose properties are very similar to those of Eta Carinae, an amazing star system that seems to have no equivalent in the Milky Way and which it is difficult to study in detail precisely because of its uniqueness. Eta Carinae i unique: 5 Eta discovered A stronomers do not really like hav- ing to deal with celestial objects of which there is a single specimen, because regardless of how thoroughly they can be investigated, the results are still lim- ited to a sole object in a single context and in a restricted evolutionary stage. A good by Michele Ferrara STELLAR EVOLUTION MARCH-APRIL 2016 example of an exotic object is Eta Carinae ( η Car), a star system 7,500 light-years from Earth, consisting of a pair of giant stars or- biting around their common centre of grav- ity in 5.54 years. Eta Carinae could be the most massive binary system of the entire Milky Way, and most certainly it is within