Free Astronomy Magazine March-April 2015

49 MARCH-APRIL 2015 STELLAR EVOLUTION E ta Carinae is without doubt one of the most interesting objects of the south- ern sky. Already catalogued in the 17 th century as a fourth magnitude star, in the following centuries it began to show an unusual behaviour by increasing its bright- ness up to magnitude 0 (approximately 40 times brighter). As astronomers were record- ing the variability of Eta Carinae, in it were taking place such disruptions capable of pro- ducing a series of titanic mass eruptions, which continued until the end of the 19 th unveils I n the back- ground and in the side video, a spectacular repre- sentation of the 1843 eruption of Eta Carinae, when the star ejected the material that formed the fa- mous bi-lobed Ho- munculus Nebula. [Gemini Obs.] century. At the height of these events, Eta Carinae became the second brightest star of the whole sky after Sirius. This situation did not, however, last long, since the cooling and condensing of the ejecta material cre- ated a giant bi-lobed cocoon all around the star, whose brightness fell below the thre- shold of visibility to the naked eye in a mat- ter of few decades, as far as reaching the eighth magnitude in the first half of the 20 th century. Afterwards the brightness gradually returned to grow, making Eta Ca-