Gem Cluster

Around the immense star Eta Carinae, a vast field of nebulosity spreads out across the background of the Milky Way in the eastern parts of Carina. From this Eta Carinae Nebula stretch lanes of shining dust, and against the backdrop of one of these dustlanes lies the Gem Cluster, one of a number of open clusters in this part of the sky. Its precise distance from the Sun is unclear, but it seems to lie somewhere between 7,600 and 8,000 light years away.

The Gem Cluster belongs to a grouping of stars known as the Carina OB1 Association, a cloud of young stars stretching across this region of space and including numerous clusters. In common with most members of this association, the stars in the Gem Cluster are primarily blue in colour (the 'OB' in the association's name refers to the blue spectral classes 'O' and 'B'). From within the approximately one hundred stars that make up the cluster, a single bright point of red light shines out against the field of blue stars: a pulsating red supergiant designated V361 Carinae.