“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,” says Macintosh.
“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 carried out its first observations last November — during an extremely trouble-free
debut for an extraordinarily complex astronomical instrument the size of a small car.
“This was one of the smoothest first light runs
Gemini has ever seen,” says Stephen Goodsell,
who manages the project for the observatory.
Figure 2.
GPI is mounted on
the Gemini South
telescope prior to first
light observations in
late 2013.
For GPI’s first observations, the team targeted
previously known planetary systems, including the well-known Beta Pictoris system; in it
GPI obtained the first-ever spectrum 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 HR
4796A. With previous instruments, only sections of this dust ring, (which may be the de-
bris remaining from planet formation), could
be seen, but with GPI astronomers can follow
the entire circumference of the ring.
Although GPI was designed to look at distant
planets, it can also observe objects in our Solar System. The accompanying test images of
Jupiter’s moon Europa, for example, can allow
scientists to map changes in the satellite’s surface composition. The images were released
at the 223rd meeting of the American Astronomical Society.
“Seeing a planet close to a star after just one
minute was a thrill, and we saw this on only
the first week after the instrument was put on
the telescope!” says Fredrik Rantakyro, a Gemini staff scientist working on the instrument.
“Imagine what it will be able to do once we
tweak and completely tune its performance.”
“Exoplanets are extraordinarily faint and difficult to see next to a bright star,” notes GPI
chief scientist Professor James R. Graham of
the University of California who has worked
with Macintosh on the project since its inception. GPI can see planets a million times fainter than their parent stars. Often described,
‘like trying to see a firefly circling a s