Figure 3.
Gemini Planet Imager’s
first light image of the
light scattered by a disk of
dust orbiting the young
star HR 4796A. This
narrow ring is thought
to be dust from asteroids
or comets left behind by
planet formation; some
scientists have theorized
that the sharp edge
of the ring is defined
by an unseen planet.
The left image (1.9-2.1
microns) shows normal
light, including both
the dust ring and the
residual light from the
central star scattered
by turbulence in the
Earth’s atmosphere. The
right image shows only
polarized light. Leftover
starlight is unpolarized
and hence removed from
this image. The light from
the back edge of the disk
is strongly polarized as it
scatters towards us.
Figure 4.
Status display
showing
wavefront sensor
(upper-left),
upper-middle
grid represents
values being
sent to lower
order deformable
mirror (woofer),
upper-right is the
GPI light-path,
lower-right grid
represents values
sent to the higher
order deformable
mirror (tweeter).
project along with the other countries of the
Gemini Observatory partnership.
Now, she says, “it is the ‘direct imaging’ planetfinding technique’s turn to make waves.”
“After years of development and simulations
and testing, it’s incredibly exciting now to be
seeing real images and spectra of exoplanets
observed with GPI. It’s just gorgeous data,”
says Marshall Perrin of the Space Telescope
Science Institute.
In 2014, the GPI team will begin a large-scale
survey, looking at 600 young stars to see what
giant planets orbit them. GPI will also be
available to the whole Gemini community for
other projects, ranging from studies of planetforming disks to outflows of dust from massive, dying stars.
“The entire exoplanet community is excited
for GPI to usher in a whole new era of planet
finding,” says physicist and exoplanet expert
Sara Seager of the Massachusetts Institute of
Technology. Seager, who is not affiliated with
the project adds, “Each exoplanet detection
technique has its heyday. First it was the radial velocity technique (ground-based planet
searches that started the whole field). Second
it was the transit technique (namely Kepler).
Looking through Earth’s turbulent atmosphere, even with advanced adaptive optics,
GPI will only be able to see Jupiter-sized planets. But similar technology is being proposed
for future space telescopes.
“Some day, there will be an instrument that
will look a lot like GPI, on a telescope in space,”
Macintosh projects. “And the images and
spectra that will come out of that instrument
will show a little blue dot
that is another Earth.”
GPI is an international
project led by the Lawrence Livermore National
Laboratory (LLNL) under
Gemini’s supervision, with
Macintosh as Principal Investigator and LLNL engineer David Palmer as
project manager. LLNL also
produced the advanced
adaptive optics system
10
GeminiFocus
January2014