Thursday 30 August 2012

M71 in Sagitta




M71 is a globular cluster, a ball of ancient stars, associated with the rather dim constellation of  Sagitta the Arrow.  M71 is located on the edge of our galaxy, the Milky Way, some 1300 light years from our planet Earth.  I took the photograph of M71 a few weeks ago, from our backyard  using  a DSLR and my Meade refracting telescope.

Until the 1970s, M71 was considered a loose open star cluster, since then it has been classified as a globular star cluster.  M71 is 27 light years across and is comprised from very old stars which have been shining for almost 10 billion years.  As the Universe only came into existence 13.4 billion years ago, these stars represent  some of the Milky Way's stellar senior citizens and as such are almost devoid of elements other than Hydrogen and Helium.  These early generation stars are said by astro-physicists to be 'metal-deficient'.

 Approximately 150 globular clusters have been identified as satellites to our galaxy. The larger globular star clusters, like M13 in the constellation Hercules, can be viewed with the naked eye and appear as small misty balls in binoculars.  On the next moonless clear night, why not go outside hunting and see if you can spot a globular star cluster?


Credit  for Starmap Wikipedia



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