October 2015
Julien Rameau and Robert De Rosa
GPI Discovers the Most
Jupiter-like Exoplanet Ever
Directly Detected
After 10 years of development, the Gemini Planet Imager (GPI)
— the most powerful of its kind — started operating routinely
in late 2013. After observing just 44 stars, GPI found its first
exoplanet — a young, cool object that is the most Jupiter-like,
and probably the lowest-mass exoplanet, ever directly imaged.
This finding will also lead to a better understanding of how our
Solar System formed.
Detecting an extrasolar planet directly from its infrared radiation is extremely challenging. This
is mainly due to two factors: (1) the large contrast in brightness between the star and planet
(around a million to one), and (2) the small angular separation between the star and planet
(under one arcsecond). Moreover, the Earth’s turbulent atmosphere strongly degrades the image quality, preventing large ground-based telescopes from reaching their theoretical diffraction limit. To overcome this detrimental effect, many world-class observatories, like Gemini,
employ high-angular resolution instruments with adaptive optics (AO) systems to both sense,
and correct for, wavefront distortions, producing extremely sharp images free from atmospheric distortions.
The first generation of AO-fed instruments discovered a handful of extrasolar planets with
contrasts of ~105, or at angular separations greater than one arcsecond. To detect fainter, lessmassive planets closer to their parent star (probing scales similar to our own Solar System),
an international team of astronomers and engineers conceived, designed, and built the most
powerful AO instrument to date: the Gemini Planet Imager (GPI) on the Gemini South telescope in Chile.
January 2016
2015 Year in Review
GeminiFocus
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