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Open Cluster NGC 2266

Date:27.10.1995 Time:00:55 UT Exposure:B:40m, V:45m, I:10m
Field of View:19.2' x 18.5' Receiver: WWFPP, 20482 CCD Filter:B, V, I
Instrument: 1.23m Observatory: Calar Alto Observer:T. Credner, S. Kohle

© Copyright by the observers

Astronomical Institutes of the University of Bonn

From Colors to Astrophysics

This three color composite is consisting of Johnson B, V, and I filter exposures, represented in blue, green, and red respectively.

The Open Star Cluster NGC 2266 lies in a distance of about 3.4 kpc towards the constellation Gemini. Its apparent diameter is just about 5'. It belongs to the population of old open star clusters in our galaxy, i.e. ages of one billion years or even older (Phelps et al., 1994). In the above image you can see this fact at the relative large number of red stars lying in the field of the cluster. Most blue stars in the cluster are "normal" hydrogen core burning stars. But many stars already left this evolutionary stage, because their central hydrogen is exhausted. Now they burn their hydrogen in a shell around the stellar nucleus and do appear as bright red giant stars. The brightest stars in the image are probably foreground stars and do not belong to the cluster population. On the left hand side you can recognize two small edge-on galaxies.


  • 1991AcA....41..191K, Kaluzny et al., The Hyades-age anticenter cluster NGC 2266
  • 1994AJ....107.1079P, Phelps et al., Development of the Galactic Disk: A search for the oldest Open Clusters
  • SEDS infos

    This image is already published in:

  • Astronomy Picture of the Day, April 29, 1999, NASA