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Microlensing with CCDs

Microlensing with CCDs. Philip Yock University of Auckland, NZ http://www.physics.auckland.ac.nz/moa/index.html NZ-Australia Semiconductor Instrumentation Workshop, June 2004. Why microlensing? – Why CCDs?. Precision measurements can be made on stars

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Microlensing with CCDs

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  1. Microlensing with CCDs Philip Yock University of Auckland, NZ http://www.physics.auckland.ac.nz/moa/index.html NZ-Australia Semiconductor Instrumentation Workshop, June 2004

  2. Why microlensing? – Why CCDs? • Precision measurements can be made on stars • Highest precision measurements on planets • Many stars must be monitored – CCDs essential

  3. Basics of microlensing Lens Source Earth EINSTEIN RING

  4. Demonstration with a glass lens • CourtesySidney Liebes, Princeton

  5. Typical astronomical dimensions 10,000 ly 20,000 ly 2 AU 1 mas

  6. Detectable in the Galactic Bulge

  7. The need for CCDs Required separation ~ 1mas, but typical separation ~1as “No chance of observing this phenomenon” - Einstein (1936)

  8. Typical CCD arrays MOA-II MOA-I 24 million pixels 80 million pixels

  9. Ground versus space MACHO 98-BLG-35 HST MOA Difference imaging essential from the ground

  10. Light curve Typical transverse velocity ~ 200 km/sec

  11. Light curve Liebes-Paczynski light curve versus data

  12. Planetary microlensing Planets perturb the Einstein ring

  13. Comparison with Rutherford scattering

  14. Planetary perturbations Neptune at 2 AU Perturbation ~ 5%

  15. Neptune at ~ 2AU at different 

  16. Earth at ~ 2 AU Perturbation ~ 0.5%

  17. Two planets Detectable if  > 20°

  18. MACHO 98-BLG-35  Magnification = 80  Possible Earth-mass planet

  19. MOA 2003-BLG-32/OGLE 2003-BLG-219 Magnification = 520 e-4 = Neptune e-5 = Earth e-6 = Mars (preliminary)

  20. MOA 2003-BLG-32/OGLE 2003-BLG-219 e-4 = Neptune e-3 = Saturn

  21. Binary lens A “caustic” is formed

  22. MOA 2002-BLG-33 MOA 0.6m 480 exp Wise 1m 20 exp MDM 2.4m 260 exp EROS 1m 186 exp Boyden 1.5m 473 exp HST 2.4m 5 exp

  23. MOA 2002-BLG-33  The light curve determines the lens geometry  The lens profiles the source

  24. MOA 2002-BLG-33  Caustic crossed in 15.6 hours  Profiles obtained, on entry and on exit

  25. Stellar profile MOA 2002-BLG33 Another star  Stellar atmosphere theory confirmed  Precision comparable to that of the VLTI - Very Large Telescope Interferometer at ESO

  26. Conclusions •  Stellar gravitational lenses exist •  Extra-solar planets detectable •  Stars resolvable •  Nature helpful!

  27. 64 million dollar question Is SU(3)SU(2)U(1) being studied on other planets?

  28. Acknowledgements •  Ian Bond & Nick Rattenbury •  John Hearnshaw & Yasushi Muraki •  Colleagues in MOA, MACHO, EROS, OGLE, FUN, PLANET •  Marsden Fund, Department of Education of Japan

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