Recent studies confirm rotation is important in Omega Centauri
, but other effects (including galactic tidal forces) might dominate in other clusters.
Paul and Liz Downing, from their observatory in southern Spain (latitude 36[degrees] 51' 42" N, longitude 3[degrees] 15m 30s W--see Journal 117(6), 2007), are able to observe both globulars--albeit with Omega Centauri
considerably closer to the horizon--and their images, made at the same scale, are shown here.
The presence of different stellar populations suggests that Omega Centauri
is not, in fact, a globular cluster, but the remnant core of a dwarf galaxy torn to shreds by the Milky Way's gravity.
Exactly 4[degrees] southwest of Omega Centauri
is long, narrow NGC 4945.
The globular star cluster Omega Centauri
has caught the attention of sky watchers ever since the ancient astronomer Ptolemy first catalogued it 2,000 years ago.
She says that Omega Centauri
may have collided at some earlier time with another cluster to create the mix of ultraviolet intensities and the lower-than-expected core density apparent in the globular cluster today.
Appearing nearly as large as the full moon on the southern night sky, Omega Centauri
is visible with the unaided eye from a clear, dark observing site.
(NGC 5139) hugs our horizon in May and can be seen as a very pale, very large, unresolved circular glow.
Globular clusters Omega Centauri
and 47 Tucanae were dazzling, and the Tarantula Nebula (NGC 2070) in the Large Magellanic Cloud (LMC) showed extensive structure and detail.
was quite hard to detect, and the images would be considered poor if you didn't allow for the object's extremely low altitude.
This is consistent with the theory that M54, like the big globular cluster Omega Centauri
, is the stripped nucleus of a former dwarf galaxy that joined into the Milky Way.
But if you live below latitude 42[degrees] north, and can find a dark spot with a clear southern horizon, you might just be able to see Omega Centauri
(NGC 5139), the sky's brightest globular star cluster.