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| Date: | 22./23.10.1995 (B&I/V) | Time: | 20:25 UT (B,I), 21:05 UT (V) | Exposure: | B:42m, V:20m, I:9m |
|---|---|---|---|---|---|
| Field of View: | 20.7' x 18.8' | Receiver: | WWFPP, 20482 CCD | Filter: | B, V, I |
| Instrument: | 1.23m | Observatory: | Calar Alto | Observer: | T. Credner, S. Kohle |
Astronomical Institutes of the University of Bonn
This three color composite is consisting of Johnson B, V, and I filter exposures, represented in blue, green, and red respectively.
M 71 is a rich but relativ small star cluster lying in the Milky Way of the
constellation Sagitta.
Its classification, whether to be of globular or open cluster type, was a long debate.
In comparison with usual globular clusters like M 10,
its star distribution is very loose but on the other hand the cluster is much
more rich and condensed than typical open clusters like
NGC 2194.
The old age of 15 Gyrs is typical for galactic globular clusters, but the
abundance of heavy elements (metallicity) is as high as in galactic plane
objects like open clusters. And the clusters orbit is also more like the one
of open clusters inside our galactic plane.
Finally, Zinn (1985) introduced an intermediate class of globular clusters that
belong to the galactic plane population and not as usual to the spherical
distributed halo population. M 71 and also 47 Tucanae
would belong to this new class.
See also: