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| M71, A Globular Cluster, - this image cropped and reduced from the original photo, Click on photo above for a full resolution image. |
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This doesn't look like a typical globular cluster, and
for a long time, the classification of M71 as a globular was uncertain. Many
astronomers thought it was a rather condensed open cluster similar to
M11, whereas others thought it was more
like the loose globular
M68.
Evidence to assign it one way or another was conflicting. Nevertheless,
there's now
consensus that M71 is a loose globular. It is 13,000 light years distant
with the majority of the stars within a 27 light year diameter, small for a globular
cluster. However, as an indication of just how loose and diffuse it is,
faint members have been detected out to a diameter
of 90 light years.
This globular cluster is fairly easy to find and fairly easy to see with binoculars. It is located high in the summer's Milky Way, north of Altair, about 1/3rd of the way to Deneb. Six inch or larger telescopes are required to resolve it into stars, some of which can be resolved all the way to the center. It contains maybe 30 bright stars scattered over a field of 7.8 arc minutes, with an overall surface brightness of magnitude 8.2. |
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11"
Celestron HDEdge, F10, moddifiied Schmidt Cassegrain Telescope, Canon Ra camera, placed at the scope's prime focus |