Direct Detection of Planets and Brown Dwarfs

N.B.

• diffraction limit for 1 meter telescope = 0.13 arcsec
• earth-sun separation at 10 pc = 0.1 arcsec
• jupiter-sun separation at 10 pc = 1.1 arcsec
• diamter of sun at 10 pc = 0.001 arcsec

Imaging Problems

• optics
  even perfect optics do not give perfect images

• glare
  stars are 10 billion times brighter than planets

• atmospheric turbulence
  blures images - very best sites have 0.8 arcsec "seeing"

Helpful Solutions

• adaptive optics
  
• coronographic cameras (+ AO)
  
• Hubble Space Telescope (diffraction limited)
  
• Image reconstruction (Speckle - diffraction limited)
  
• Stellar interferometers (mirror separation limited)

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(SETI)

Hearing from our neighbors (visitation?)
Project Phoenix at Parkes - 16 weeks of false alarms

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