Trapezium Cluster
The Trapezium or Orion Trapezium Cluster , also known by its Bayer designation of Theta1 Orionis , is a tight open cluster of stars in the heart of the Orion Nebula , in the constellation of Orion . 
<triplet> Trapezium Cluster <subj> Orion <obj> constellation <triplet> Orion Nebula <subj> Orion <obj> constellation <triplet> Orion <subj> constellation <obj> instance of