Animation of the path that an incoming light ray traces through the GRAVITY instrument. Note the intricate design and complex interaction of the various components for the four telescopes. For interferometry to work, the light paths have to be superposed with a precision of a fraction of the wavelength – less than 1 micrometer.
Zooming in on black holes is the main mission for the newly installed instrument GRAVITY at ESO’s Very Large Telescope in Chile. During its first observations, GRAVITY successfully combined starlight using all four Auxiliary Telescopes.
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.
Two views of the Trapezium cluster in the Orion Nebula, from the Hubble Space Telescope The image on the left, an optical spectrum image taken with Hubble’s WFPC2 camera, shows a few stars shrouded in glowing gas and dust. On the right, an image taken with Hubble’s NICMOS infrared camera penetrates the haze to reveal a swarm of stars as well as brown dwarfs. Source: http://hubblesite.org/newscenter/newsdesk/archive/releases/2000/19.
The entire Orion Nebula in visible light. By Hubble.
Already, from these first commissioning data, GRAVITY made a small discovery: one of the components of the cluster was found to be a double star .
In particular, GRAVITY will probe what happens in the extremely strong gravitational field close to the event horizon of the supermassive black hole at the centre of the Milky Way — which explains the choice of the name of the instrument. This is a region where behaviour is dominated by [Albert] Einstein’s theory of general relativity. In addition, it will uncover the details of mass accretion and jets — processes that occur both around newborn stars (young stellar objects) and in the regions around the supermassive black holes at the centres of other galaxies. It will also excel at probing the motions of binary stars, exoplanets and young stellar discs, and in imaging the surfaces of stars.