SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch), a new instruments that combines different advanced techniques to directly photograph planets in other solar systems, has been activated for its test phase. At the end of 2013 scientists verified that it worked in Europe and they shipped it to Chile to be installed on ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile.
SPHERE’s main task is to discover and examine giant planets orbiting nearby stars. This is difficult because they are very close to them and their light is much dimmer. For this reason, generally the planets are discovered through indirect methods, for example by analyzing the drop in a star’s light when a planet passes in front of it. SPHERE is designed to achieve maximum contrast in a tiny area around the star to be able to directly observe its planets.
SPHERE’s operation is based on the combination of three really sophisticated techniques. The first takes advantage of an extremely adaptive optics to correct the interference caused by Earth’s atmosphere to get a clearer picture. The second uses a coronagraph to eliminate the light from bright sources to obtain an even greater contrast. The third technique, called differential imaging, exploits the differences between the light of the star and that of the planet in terms of color or polarization to detect the presence of otherwise invisible planets.
SPHERE is an instrument designed and built by an international collaboration among different institutes: Institut de Planétologie et d’Astrophysique de Grenoble; Max-Planck-Institut für Astronomie in Heidelberg; Laboratoire d’Astrophysique de Marseille; Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique de l’Observatoire de Paris; Laboratoire Lagrange in Nice; ONERA; Observatoire de Genève; Italian National Institute for Astrophysics coordinated by the Osservatorio Astronomico di Padova; Institute for Astronomy, ETH Zurich; Astronomical Institute of the University of Amsterdam; Netherlands Research School for Astronomy (NOVA-ASTRON) and ESO
The first SPHERE tests in Chile have already given excellent results, not only in the search for giant exoplanets. For example, it allowed to take the best photographs made so far of the dust ring around the star HR 4796A, about 237 light years from Earth. This test also confirmed that SPHERE is very good at eliminating the bright light of a star.
This is just the beginning of SPHERE’s work. Its activation is a further progress in the research and study of exoplanets, which is giving us the opportunity to know the universe in a way that until a few years ago was unthinkable.