GPI imager

Disque de poussières en orbite autour de la jeune étoile HR4796A. (Source : Marshall Perrin)

Dust disk orbiting young star HR4796A. (Source: Marshall Perrin)

The Gemini Planet Imager (GPI) is an instrument capable of detecting infrared light emitted by Jupiter-like gas giants orbiting their host stars, similar to the gas giants in our solar system when it formed. The GPI boasts the world’s most advanced technology for imaging exoplanets. It is optimized for imaging faint planets near their stars, probing their atmospheres and studying the debris disks around these stars. It also has a spectroscopic mode for studying planets in greater detail. The instrument is deployed on the Gemini South telescope in Chile, one of the largest in the world.

The first GPI images were a factor of 10 better than those taken with the previous generation of instruments. The GPI captured its first cosmic photons last November during its first-light run. On this first run the team of researchers managed to observe the Beta Pictoris planet-star system and the very first spectrum from the exoplanet Beta Pictoris b (Figures 1 and 2).

Figure 1. Beta Pictoris b, taken with the NICI instrument on the Gemini South telescope, with an exposure of 4,000 seconds (image processing by Christian Marois, NRC Canada).

Figure 2. GPI first-light image, of Beta Pictoris b, with an exposure of 900 seconds. The bright star Beta Pictoris, the sun of the giant planet, is hidden behind a mask in the centre of the image. A few diffuse light artifacts (or speckles) are visible around the masked star, but much less than with the NICI instruments (image processing by Christian Marois, NRC Canada).













In 2014, the GPI team will begin a large-scale survey, looking at 600 young stars to discover and study potential planetary systems. The GPI will also be available to the whole Gemini community for other projects, ranging from studies of planet-forming disks to outflows of dust from more massive stars.

Fruit of international collaboration

GPI is an international project led by Bruce Macintosh, as Principal Investigator, and David Palmer, as Project Manager, both of the Lawrence Livermore National Laboratory (LLNL). Scientists at the American Museum of Natural History, led by Rebecca Oppenheimer, designed special masks that are part of the instrument’s coronagraph which blocks the bright starlight that can obscure faint planets. Engineer Kent Wallace and a team from NASA’s Jet Propulsion Laboratory constructed an ultra-precise infrared wavefront sensor to measure small distortions in starlight that might mask an exoplanet.

A team at the University of California Los Angeles’ Infrared Laboratory, under the supervision of Professor James Larkin, in close collaboration with Professor René Doyon of the Department of Physics at the UdeM and Professor Simon Thibault of Université Laval, designed, assembled and tested the infrared spectrograph that dissects the light from planets. Staff at the Observatoire du Mont-Mégantic, the Institut national d’optique in Québec City and Immervision, a Montreal company, were also involved in developing the spectrograph.

The powerful data analysis software, designed and developed at the Université de Montréal in co-operation with the Dunlap Institute in Toronto and the Space Telescope Science Institute and the National Research Council – Herzberg, assembles the spectral data from each pixel into three-dimensional cubes.

Lastly, the National Research Council – Herzberg in British Columbia designed and built the mechanical structure and software that knits all the pieces together. The instrument underwent extensive testing at the University of California Santa Cruz before it was shipped to Chile in August. The SETI Institute  manages the GPI’s data and communications.