The “Southern Pleiades”

April 15, 2009

This time of year, in the rich star fields of the deep southern constellation Carina, you’ll find numerous sights to hold your attention.  Today we tour the Theta Carinae cluster, also called the “Southern Pleiades” because of its astronomical resemblance to the famed northern star cluster M45 in Taurus.



The Basics

• First off, this star cluster is NOT dipper-shaped like the Pleiades.  It’s much less regular, with two distinct groupings of stars.  But it resembles the Pleiades in many other ways.

• Like M45, many of this cluster’s brightest constituents, including the star theta Carinae itself and the 4th magnitude star V518 Carinae, are easily visible with the naked eye.  In all, the Theta Carinae cluster has about 10 stars brighter than 6th magnitude.

• Also like the Pleiades, this cluster is quite young… just 30 million years old.  It’s some 500 light years away versus 450 light years for the Pleiades.  And like M45 it’s 15 light years across.

• This cluster, like the Pleiades, is best viewed with binoculars or a wide-field telescope at low power.

IC 2602, the “Southern Pleiades”, above center

A Deeper Look

• Most of its 60 members are bright blue A and B-type stars, like M45.  But astronomers worked extra hard determining which stars belong to the cluster, and which are merely foreground and background stars in this dense section of the Milky Way.

• The cluster, catalogued formally as IC2602, is found in the deep southern skies at RA 10h 43m and Dec -64d24m.  You’ll have a hard time seeing even from Hawaii or India.  For a good look, south of the equator is where you need to be.

• Like many southern star clusters, the southern Pleiades were discovered by the diligent French astronomer Louis de Lacaille in 1755 during his star mapping sessions in South Africa.

Bonus Object

There are no shortages of things to see in this stretch of sky.  Just 3/4-degree south of the “Southern Pleiades”, look for another small open cluster called Meloitte 101.

Personal View

Like many things in the southern hemisphere, I’ve only seen this cluster briefly and without optical aid.  But the sights in and around Carina will draw you in and demand closer examination.  In dark sky, this star-strewn section of the Milky Way is so spectacular, it’s hard to look away.

Posted in Celestial Objects