ADAPTIVE OPTICS IN ASTRONOMY

1. 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.

2. ADAPTIVE OPTICS IN ASTRONOMY THE SOLUTION: Use expensive small space-based telescopes like the Hubble space telescope. Use cutting-edge opto-mechanical instrumentationto 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.

3. Here is a movie showing a schematic of the Gemini North Telescope Adaptive Optics System on Mauna Kea Hawaii (Credit Gemini, NSF, & Aura)

4. 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

5. 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: The Sun, Asteroids, planets, moons, comets Nearby stars, disks around young stars, clusters of stars The black hole at the center of the Galaxy Nearby galaxies, active galactic nuclei, quasars and their host galaxies Graves et al. 1998; Close et al. 1998

6. ADAPTIVE OPTICS IN ASTRONOMY The Sun with the Swedish 1.0 meter AO solar telescope (Scharmeret al.)

7. 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).

8. 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).

9. 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)

10. 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)

11. 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.

12. 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)