The constellation of Carina is host to a nebula around the star Eta Carina. This star had a massive outburst in 1843 and was the second brightest star in our skies (after Sirius) for a few months. Eta Carina has regular outbursts, about every five and a half years and it is expected to perform for us again in the not so (astronomically) distant future.
It was only discovered in 2005 that Eta Carina is in fact a binary system with the two stars orbiting each other at a distance of about 10 times the distance between Earth and the Sun. This is very close for two stars that are likely to be about 100 times the mass of the Sun.
Eta Carina is the bright star at the top left of the nebula in the view below. North is at the top.
I took this photo of the Carina Nebula from a dark site, 10km east of Woodside in the Adelaide Hills. This is a single image taken with a Canon 60mm macro lens at f/3.2 with an exposure time of 45 seconds at ISO 1600 on a home made star tracker. The image was processed with Photoshop CS2 and Lightroom 4.