Museum-Built Device Helping Astronomers Search for Exoplanets
by AMNH on
After nearly a decade of development, construction, and testing, the Gemini Planet Imager (GPI) is pointing skyward and collecting light from distant worlds with the help of a special starlight-blocking device, called a coronagraph, built at the American Museum of Natural History.
Installed on one of the world’s biggest telescopes, the 8-meter Gemini South telescope in Chile, the Gemini Planet Imager (GPI) carried out its first observations in November 2013. The results were released today at the 223rd meeting of the American Astronomical Society, in Washington, DC.
Constructed by a core team of researchers from seven institutions, GPI detects infrared (heat) radiation to image faint Jupiter-like planets next to bright stars and to probe their atmospheres. It also can help researchers examine dusty disks around young stars.
At the American Museum of Natural History, scientists led by Curator Rebecca Oppenheimer designed and built GPI’s coronagraph—a starlight suppression system—using a variety of experimental optics.
“The planets we seek to study are more than a million times fainter than the stars they orbit,” Oppenheimer said. “Our work on starlight suppression over the past 15 years has led to the capability to see such planets using novel types of optics and new techniques for controlling light.”
The first observation targets for GPI were previously known planetary systems including the Beta Pictoris system, which is about 63 light years away. GPI obtained the first spectrum, or chemical fingerprint, of the very young planet Beta Pictoris b. The first-light team also used the instrument’s polarization mode, which can detect starlight scattered by tiny particles, to study a faint ring of dust orbiting the very young star HR4796. With previous instruments, only the edges of this dust ring, which may be the debris remaining from planet formation, could be seen. But with GPI, astronomers can follow the entire circumference of the ring.
The group also observed the system of planets orbiting HR8799, a star about 128 light years away.
Another very similar instrument, Project 1640, led by the American Museum of Natural History, was deployed at Palomar Observatory’s 5-meter Hale Telescope in California last year and has demonstrated the power of these techniques on a smaller telescope in the Northern Hemisphere. The two instruments are complementary, and collaboration will begin with the launch this year of GPI’s large-scale survey, which will look at 600 young stars to see what giant planets orbit them.