Transcript Document

ADAPTIVE OPTICS IN ASTRONOMY
THE PROBLEM:
Since Newton’s time it was realized that the mixing of hot
and cold air “blurs” starlight passing to the surface of the
Earth.
Hence ground-based telescopes, regardless of size, are
similarly limited in their ability to make sharp images.
Speaker:
Laird Close
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
1)
2)
THE SOLUTION:
Use expensive small space-based telescopes like the
Hubble space telescope.
Use cutting-edge opto-mechanical instrumentation to
correct (in real time) distortions caused by the
atmospheric blurring. Such “adaptive” correction is
known as adaptive optics.
NOTE: Modern 8-10 meter class telescopes equipped with
adaptive optics can make images up to 4 times sharper
than the 2.4 meter Hubble Space Telescope.
Speaker:
Laird Close
University of Arizona
Here is a
movie
showing a
schematic
of the
Gemini
North
Telescope
Adaptive
Optics
System on
Mauna
Kea
Hawaii
(Credit
Gemini,
NSF, &
Aura)
Speaker:
Laird Close
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
Here is a movie
(by Buzz
Graves, AOptix)
of the
University of
Hawaii AO
system,
Hokupa’a, going
from AO “off” to
correction “on”.
The mirror must
change shape
1200 times
each second to
correct the
atmosphere
Speaker:
Laird Close
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
Astronomical Adaptive Optics Science
With adaptive optics (AO) all large ground
based telescopes can now reach their
theoretical resolution limit. Hence 8
meter AO equipped telescopes (like
Gemini) can read a license plate 20
miles away (this is 20 times farther
than without AO).
For astronomical science adaptive optics has
made the sharpest, clearest images of:
1)
The Sun, Asteroids, planets, moons,
comets
2)
Nearby stars, disks around young
stars, clusters of stars
3)
The black hole at the center of the
Galaxy
4)
Nearby galaxies, active galactic nuclei,
quasars and their host galaxies
Speaker:
Laird Close
Graves et al. 1998; Close et al. 1998
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
The Sun
with the
Swedish
1.0 meter
AO solar
telescope
(Scharmer
et al.)
Speaker:
Laird Close
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
Binary Asteroids
By following the
orbit of two
asteroids we can
solve for the
asteroid’s density
and understand its
composition
(Merline et al. 1999;
Close et al. 2000).
Speaker:
Laird Close
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
Here we see
a movie of
Jupiter’s
moon Io with
its volcanoes
(Keck AO;
Marchis et al.
2002).
The gas giant
Neptune
without then
with AO
correction
(Keck AO;
CfAO web
page).
Speaker:
Laird Close
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
AO can
sharpen all
the stars in a
field. Here is a
movie of
“turning on”
AO at the
Keck telescope
imaging the
massive black
hole at the
center of our
galaxy.
(Ghez et al.
2002)
Speaker:
Laird Close
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
Planets Around Other Stars
Here we see a Gemini AO
image of a brown dwarf around
a star (Liu et al. 2002)
And a planetary mass
companion to a brown dwarf,
which is most likely a
background source (Close et al.
2003)
Speaker:
Laird Close
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
THE FUTURE: Direct
Imaging of Planets
Around Other Stars
By building special AO
cameras we can remove
much of the “blinding
glare” of a star and
reveal any gas giant
planets in orbit around
that star. Here are
typical images from an
new “Simultaneous
differential Imager”
(SDI) on the 8 meter
VLT in Chile (Close et al.
2003; Lenzen et al.
2003)
Speaker:
Laird Close
This new SDI AO camera can image a 2 Jupiter mass planet at 4, 6,
8 and 10 “earth-SUN” distances (AU) around the 10 Million year old
star shown here. This is impossible with Classical AO alone.
University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
THE FUTURE:
Adaptive
Secondaries
The University of
Arizona has pioneered
the development of
making the secondary
mirror of a telescope
the “rubber” or
deformable mirror in
the AO system. This
open new science
fields –like AO imaging
in the thermal IR.
(Wildi et al. 2003)
RV Boo’s disk (Biller et al. 2004)
Speaker:
Laird Close
University of Arizona