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Polarizing Coronagraph for Circumstellar Dust Observations

Polarizing Coronagraph for Circumstellar Dust Observations. Polarizing Coronagraph for Circumstellar Dust Observations by Göran Olofsson, Astronomy, SU Thursday the 16th of November 10.00 o'clock at FA32 Abstract

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Polarizing Coronagraph for Circumstellar Dust Observations

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  1. Polarizing Coronagraph for Circumstellar Dust Observations Polarizing Coronagraph for Circumstellar Dust Observations by Göran Olofsson, Astronomy, SU Thursday the 16th of November 10.00 o'clock at FA32 Abstract The idea that there exists planetary systems other than that of the Sun is old, but it has until recently been beyond the technical feasibility to get any observational evidence for external planetary systems. By the IRAS discovery of far-IR dust emission around nearby stars, like Vega, it was realized that the dust replenishment required larger colliding or evaporating bodies, i.e. processes similar to those that provide the zodiacal dust. In addition, a steadily increasing number of planets are being found by detecting the minimal cyclic radial velocity variations of the central star caused by an orbiting planet. Obviously this (indirect) detection method works bests for heavy planets, orbiting close to their central stars, and there is an ongoing discussion what technical means it may take to do direct detection of planetary systems similar to our own. It has been argued that a new generation of extremely large ground-based telescopes (ELTs) may provide the tool for such observations (actually this is one of the main scientific drivers for the large investments required to build ELTs). But probably we have to wait for space interferometers, like Darwin, for the first detection of an Earth like planet orbiting an nearby star. Until then, much closer in time, we can explore the properties of circumstellar dust disks, and I will describe our own plans in that direction, both using Herschel Space Observatory and a 'home-made' polarizing coronagraph.

  2. Vega (IRAS)

  3. Disk evolution

  4. Silhouette disks

  5. silh2

  6. silh3

  7. Silh4

  8. Disk evolution

  9. betaPic_0.5µm

  10. betaPic_10µm

  11. A smooth decline of dust with time?

  12. ISO view

  13. Spitzer sample Age N*/Ntot Distance (pc) Target The Spitzer sample

  14. Spitzer_FEPS FEPS, only 15 stars with excess at 24 µm

  15. Herschel will see cold dust Cold dust - little or plenty? ? ?

  16. Disk evolution

  17. Kuiper belt The Sun+Kuiper belt at distance Contrast ratio Ldust/Lsun

  18. Planets, radial velocity

  19. Orbits

  20. Mass distribution

  21. PSF

  22. Lyot Coronagraph Focal plane Relay lens Pupil stop EMCCD

  23. Seeing 0.7”, disk 1” diam Pupil image

  24. Seeing 0.7” disk =1”

  25. Seeing 0.7”, disk 3” diam Pupil image

  26. Seeing 0.7” disk 3”

  27. PSF, coronagraph

  28. Observed PSF

  29. Lyot Coronagraph Focal plane Relay lens Pupil stop polarizer EMCCD

  30. NGC 7023

  31. Image sharpening

  32. Frame selection + MEM Shift-and-add, 20% MEM, 33 iterations PSF star

  33. Zoom PSF star

  34. betaPic

  35. Gas component Gas component TW Hya, 10 Myr B Pic, 10-20 Myr

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