Throughout the previous blog posts I have mentioned the term
globular cluster in reference to some of the Messier objects. A globular cluster is a gravitationally bound group of stars that may contain millions of individual stars up to tens or a hundred light years across. Since the cluster is bound by gravity it has a unique spherical shape that makes it a beautiful sight through a telescope. Globular clusters tend to reside in the Milky Way's
galactic halo. The galactic halo is essentially the spherical component of a galaxy outside the plane of the spiral arms. An image borrowed from Durham University shows this halo region with the globular clusters.
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| Globular Clusters in the Galactic Halo (Milky Way) |
Omega Centauri is known to be our galaxy's largest globular cluster. It was first discovered by Ptolemy around 150AD. It has a radius of 150 light years and contains around 10 million stars. It may have been the core of a dwarf galaxy torn apart by our own Milky Way's gravity. At one time it was theorized that an intermediate mass black hole resided at the center of the cluster. Unfortunately it is too far south on the celestial sphere to be visible to residents of Calgary.
One of my favourite globular clusters visible from Calgary is shown below in an image I recently took. Messier 2 is a globular cluster located in my astrological zodiac constellation of Aquarius. It was beautiful, you could make out individual stars in the sphere of more than 150,000 stars.
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| Messier 2 (M2) |
Another great globular cluster is the Hercules Cluster. Also known as
Messier 13, it shines brilliantly in the constellation of Hercules. Below is an image from our backyard.
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| Messier 13 - Hercules Cluster |
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