Powerful Exoplanet Camera Unveiled

After nearly a decade of development, a powerful exoplanet camera that detects IR radiation to image and analyze planets from other solar systems is now operational.

The Gemini Planet Imager (GPI), developed by a team of scientists from the Lawrence Livermore National Laboratory (LLNL), under the supervision of the Gemini Observatory, is now in use on the 8-m Gemini South telescope in La Serena.

The first light image of Beta Pictoris b, a planet orbiting the star Beta Pictoris, was captured by the new GPI. GPI also obtains a spectrum from every pixel element in the field of view, allowing scientists to study the planet in great detail. Courtesy of NRC Canada.

The instrument, about the size of a small car, detects IR radiation from young Jupiter-like planets in wide orbits around other stars. It is used for imaging exoplanets around bright stars and analyzing their atmospheres, as well as to study planet-forming disks around young stars. According to GPI chief scientist and professor James Graham of the University of California, GPI can see planets a million times fainter than their parent stars.

“Even these early first-light images are almost a factor of 10 better than the previous generation of instruments,” said LLNL team leader Bruce Macintosh. “In one minute, we are seeing planets that used to take us an hour to detect.

GPI’s first light image of the light scattered by a ring of dust that orbits the young star HR4796A. This narrow ring is thought to be dust from asteroids or comets left behind by planet formation. The left image shows normal light, while the right shows only polarized light. Courtesy of Space Telescope Science Institute.

“Most planets that we know about to date are only known because of indirect methods that tell us a planet is there, a bit about its orbit and mass, but not much else. With GPI we directly image planets around stars. It’s a bit like being able to dissect the system and really dive into the planet’s atmospheric makeup and characteristics.”

GPI’s first observations were taken in November. The LLNL team targeted known planetary systems, including the Beta Pictoris system, where it captured the first spectrum of the young planet Beta Pictoris b.

The camera’s polarization mode, which can detect starlight scattered by tiny particles, was also used to study the entire circumference of a faint ring of dust that orbits a young star nearby. This dust may be debris remaining from planet formation, according to astronomers. Prior to GPI, only the edges of that dust ring could be seen.

GPI can also observe objects in our own solar system; a test image taken with GPI of Jupiter’s moon Europa helped scientists map changes in the satellite’s surface composition.

On the right is a comparison of Jupiter’s moon Europa, observed using GPI in K1 band. On the left is albedo visualization based on a composite map made from Galileo SSI and Voyager 1 and 2 data. While GPI is not designed for objects like this, its observations could help in following surface alterations on icy satellites of Jupiter or atmospheric phenomena such as clouds or haze on Saturn’s moon Titan. Courtesy of Space Telescope Science Institute and Franck Marchis SETI Institute.

This year, the GPI team will begin a large-scale survey, looking at 600 young stars to see what giant planets orbit them. GPI also will be available to the entire Gemini community for other projects, ranging from studies of planet-forming disks to outflows of dust from massive, dying stars.

Currently, GPI can only see larger planets equivalent in size to Jupiter due to the view through Earth’s turbulent atmosphere. Technology has been proposed for cameras and telescopes that would operate similarly to GPI yet be able to focus on smaller planets and related objects.

“Someday, there will be an instrument that will look a lot like GPI, on a telescope in space,” Macintosh said. “And the images and spectra that will come out of that instrument will show a little blue dot that is another Earth.”

For more information, visit www.gemini.edu.