This photo shows a colour composite mosaic image of the central part of the Orion Nebula, based on 81 images obtained with the infrared multi-mode ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory. The famous Trapezium stars are seen near the centre and the photo also shows the associated cluster of about 1,000 stars, approximately one million years old.
The Trapezium is a relatively young cluster that has formed directly out of the parent nebula. The five brightest stars are on the order of 15-30 solar masses in size. They are within a diameter of 1.5 light-years of each other and are responsible for much of the illumination of the surrounding nebula. The Trapezium may be a sub-component of the larger Orion Nebula Cluster, a grouping of about 2,000 stars within a diameter of 20 light-years.
The cluster has an apparent magnitude of 4.0 and lies at a distance of 1,600 light years from Earth. It occupies an area of only 47 arc seconds of apparent sky.
Also known as the Orion Trapezium Cluster or Theta-1 Orionis, the Trapezium Cluster can be resolved in 5-inch telescopes, which reveal six of the cluster’s stars in good observing conditions. The cluster is easy to identify because the brightest four stars form an asterism shaped like a trapezoid.