1 / 44

This page is intentionally blank

This page is intentionally blank. Big Telescopes. for a Small World. A new view of the Universe II Fred Watson, AAO April 2005. Big Telescopes for a Small World. The secret obsessions of astronomers. Characteristics of astronomy today. Highly comprehensive range of instrumentation

eve-le
Télécharger la présentation

This page is intentionally blank

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. This page is intentionally blank

  2. Big Telescopes for a Small World A new view of the Universe II Fred Watson, AAO April 2005

  3. Big Telescopes for a Small World The secret obsessions of astronomers

  4. Characteristics of astronomy today • Highly comprehensive range of instrumentation • Infinite computing power • Access to every part of the electromagnetic spectrum:-rays,X-rays,UV,visible (optical),IR,mm-wave,radio • Not to mention particles, gravitational waves… (So we won’t.) Big Telescopes for a Small World

  5. The Universe through different eyes... Big Telescopes for a Small World

  6. What’s so good about opticalastronomy? • Visible light is emitted by ‘ordinary matter’ in the Universe—i.e. stars • The visible spectrum is rich in the ‘bar-code’ of atomic and molecular features • Optical observations bridge long and short wavebands • You can do it with your feet on the ground Big Telescopes for a Small World

  7. The Schematic Ground-Based Optical Telescope • Something large to collect and focus the radiation • A complicated bit in the middle for analysis • An optical detector • A ground-based mounting Big Telescopes for a Small World

  8. Detectors… Big Telescopes for a Small World

  9. Astronomical cameras are not small…(This is IRIS2, a multi-purpose infrared camera on the AAT)

  10. Subtracting the sky…

  11. Other complicated bits… Spectrographs conventionally use a grating, prism or grism Sends light of different wavelengths in different directions… Hence (via the spectrograph camera) to different positions on the detector (which is a CCD or an infrared array). (This slide and the next three courtesy Gordon Robertson)

  12. Reflection grating spectrograph (schematic) collimator slit grating  b cc  d i detector camera Big Telescopes for a Small World

  13. Volume phase holographic (VPH) gratings • 3-d modulations of refractive index in gelatin layer • Peak efficiency up to ~90% • Wavelength of peak efficiency can be tuned • Transmission gratings • DCG layer (hologram) is protected on both sides • Each grating is an original, made to order • Large sizes possible Big Telescopes for a Small World

  14. Test of a prototype VPH grating Big Telescopes for a Small World Note: no antireflection coatings

  15. Why make telescopes ever bigger? • To gather more light from faint sources because there are no further gains to be made in detector sensitivity • To improve resolution: R= 1.22 / D As the mirror diameter Dgets bigger, the resolution R gets finer.

  16. Large Telescope Mirror, 1969

  17. A 3.9-metre mirror can resolve 0.03 arcsec BUT… r0is Fried’s parameter for wavefront distortion Cn2is the refractive index structure constant Cn2 is integrated over the full height of the atmosphere

  18. 1 arcsecond The end-product is… This is very depressing indeed 

  19. Big Telescopes for a Small World Can you do anything useful in such conditions?

  20. Detection of extra-solar planets

  21. The answer to life, the Universe and everything... Spectrograph Slit Detector Multi-object spectroscopy with fibre optics

  22. Basic building-blocks of the Universe If this was our Galaxy, we’d be here Galaxies… • Around 100,000,000,000 stars • Lots of gas and dust (in spirals) • Around 100,000 light years across (or 1,000,000,000,000,000,000 km)

  23. Big Telescopes for a Small World Antidotes to atmospheric turbulence

  24. The Eagle Nebula—stellar birthplace

  25. But – the Hubble project’s total cost is$US 6 billion. That would buy 60 of today’s ground-based 8-metre telescopes…

  26. The world’s largest telescopes, 2005

  27. The crowded summit of Mauna Kea

  28. Antu, Kueyen, Melipal and Yepun

  29. It’s all to do with atmosphere… 1 arcsecond But at the VLT, on the same scale…

  30. Big Telescopes for a Small World What do we do next?

  31. The thinking goes like this…

  32. VLT: Very Large Telescope 4×8 m (16 m equiv.) ELT: Extremely Large Telescope 25 m CELT: California Extremely Large Telescope 30 m GSMT: Giant Segmented-Mirror Telescope 30m TMT: Thirty-metre Telescope (US + Canada + ?) Euro50: formerly SELT… Future plans for large telescopes...

  33. OWL—Sharp-eyed and OverWhelmingly Large

  34. Big Telescopes for a Small World …And what can we do with such monsters?

  35. What might we study with OWL? Earth-like planets out to about 75 l.y. by direct imaging Individual stars in moderately distant galaxies – galactic archaeology Galaxies forming at look-back times up to 10 billion years Exploding stars at look-back times up to 12.5 billion years

  36. Not to mention the completely unexpected …

  37. Big Telescopes for a Small World The End

More Related