Friday, 31 August 2012

M39 in the Constellation Cygnus


The open star cluster M39 as photographed from our backyard last summer
As the Milky Way runs through Cygnus the Swan, M39 is seen against a background of stars.
The 50 or so stars that make up M39 probably condensed from a common molecular cloud some 270 million years ago.  The loose open cluster is approximately 7 light years across and can be seen, with individual stars resolved, through 7x50 mm. binoculars.

All the stars in M39 have been determined main sequence stars on the Hertzsprung- Russell diagram, with the brighter members being on the threshold of becoming red giant stars.

The whole cluster has a proper motion of 0.024 seconds per year and is moving towards us at 28km/sec.


Hertzsprung- Russel Diagram (Credit Wikipedia)

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