Monday, September 3, 2012

Globular Cluster Photo Series (Part 22): M68

Today I have a picture of the globular cluster Messier 68, located in the constellation Hydra.

Since globular clusters orbit the center of the galaxy like everything else in it, the vast majority of them are found in the hemisphere containing the galactic core. Messier 68 is an oddity, a large globular cluster found in the hemisphere opposite the galactic center. Physically, it is about 106 light-years in diameter, and appears about 11.0 arc-minutes across on the sky (about a third of the width of the full Moon). It is located at the not-too-shabby distance of 33,300 light-years from us, and given that it is further from the core than we are, it is perhaps not too surprising that it is approaching us at 112 kilometers/second. M68 contains a fairly average number of 42 variable stars (discovered so far).

Messier 68 in Hydra.
Hydra is pretty far south for a Messier object (declination –26° 44′ 38.6″), and as a result observers in the mid- to far-northern hemisphere tend to see it through a lot of atmosphere low on the horizon, which often led past observers to estimate its brightness as fainter than it really was. Thankfully, being in Hawai‘i means that I can see it pretty well. And other than that, there really isn't too much to say about it. A hui hou!

1 comment:

  1. U did good job! Even small from the earth, there are certainly in the Cosmo ! So pretty <3
    Toshie from Japan now


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