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Speaker: Laird Close University of Arizona
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
THE SOLUTION: 1) Use expensive small space-based telescopes like
the Hubble space telescope.2) 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.
ADAPTIVE OPTICS IN ASTRONOMY
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
Graves et al. 1998; Close et al. 1998
Speaker: Laird Close University of Arizona
ADAPTIVE OPTICS IN ASTRONOMY
The Sun with the Swedish
1.0 meter AO
solar telescope(Scharme
ret 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)
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.
Speaker: Laird Close 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)