Free Astronomy Magazine March-April 2016

SPACE CHRONICLES A s part of the first observations with the new GRAVITY instrument the team looked closely at the bright, young stars known as the Trapezium Cluster, located in the heart of the Orion star-forming region. Already, from these first data, GRAVITY made a discovery: one of the components of the cluster (Theta1 Orionis F) was found to be a double star for the first time. The brighter known double star Theta1 Orionis C is also well seen. The background image comes from the ISAAC instru- ment on ESO's Very Large Telescope. The views of two of the stars from GRAVITY, shown as inserts, reveal far finer detail than could be detected with the NASA/ESA Hubble Space Telescope. [ESO/GRAVITY consortium/NASA/ESA/M. McCaughrean] angular resolution astronomy to new limits, far beyond what is cur- rently possible.” As part of the first observations the team looked closely at the bright, young stars known as the Trapezium Cluster, located in the heart of the Orion star-forming region. Already, from these first commissioning data, GRAVITY made a small discovery: one of the components of the clus- ter was found to be a double star. The newly discovered double star is Theta1 Orionis F, and the observa- tions were made using the nearby brighter star Theta1 Orionis C as the reference. The key to this success was to stabilise the virtual telescope for long enough, using the light of a reference star, so that a deep ex- posure on a second, much fainter object becomes feasible. Further- more, the astronomers also succeed- ed in stabilising the light from four