The Seven Sisters of the South

Down in the south sit many austral equivalents to namesake northern sky objects: the Southern Cross, the Southern Beehive, the Southern Pinwheel. This is the “Southern Pleiades,” a match to the famous Pleiades star cluster prominent in our northern hemisphere sky. Since our Pleiades also carries the moniker the “Seven Sisters,” I suppose that makes this object the “Seven Sisters of the South.”

The field here again duplicates what binoculars would show, and this is a lovely object for binos. Its resemblance to the northern Pleiades comes from this star cluster’s bright but scattered appearance, and the blue colour of its sorority of stars. Like its northern counterpart, the Southern Pleiades is a cluster of hot young stars which shine furiously blue in their energetic youth. This group is perhaps no more than 50 million years old, and like the northern Sisters, shines quite close by, just 480 light years away, putting it a stone’s throw away down our own galactic spiral arm.

Officially catalogued as IC 2602, and also dubbed the Theta Carinae Cluster, this clutch of blue stars shines just below the Carina Nebula (you can see both together in my earlier blog The Best Nebula in the Sky). A couple of other fainter star clusters also populate the field.

I took this shot with the Canon 7D and 135mm telephoto lens and stacked five 2-minute exposures. Stacking helps smooth out background noise, though in a wide field shot like this, the sheer number of stars tends to overwhelm any camera noise.

— Alan, June 4, 2011 / Image © 2011 Alan Dyer