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Extrasolar planet detection: Methods and limits

Extrasolar planet detection: Methods and limits. Ge/Ay133. Spectral Energy Distributions (or, Blinded by the light!...). How do you find a planet?. Look for it? Hard (as we’ve seen)!. Only planets imaged are very young and far from their stars. Are such objects

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Extrasolar planet detection: Methods and limits

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  1. Extrasolar planet detection: Methods and limits Ge/Ay133

  2. Spectral Energy Distributions (or, Blinded by the light!...)

  3. How do you find a planet? • Look for it? Hard (as we’ve seen)! Only planets imaged are very young and far from their stars. Are such objects common or rare?

  4. How do you find a planet? • Look for it? Hard! • Where should you look? Few AU? • Look for its affect on the star? (Indirect)

  5. 200 mas Astrometric displacement of the Sun due to Jupiter as seen from a distance of 10 pc (Current state of the art w/Keck AO = 200 mas, as of 2007)

  6. Discovery space for indirect methods: Radial velocity Astrometry (r=distance to the star)

  7. Radial velocity signature is distance independent (S/N is not!) First (written) proposal by Otto Struve,The Observatory 72, p. 199-200 (1952) 51 Peg announced in 1995 (PSR 1257+12 in 1992). .

  8. Spectroscopy with Echelles: Keck Photons have come a long way, don’t lose them! Echelle spectrometers in conjunction with large format arrays can provide R~30,000-100,000 spectra across the entire visible or near-IR range (l<5 mm, good for late type stars and brown dwarfs).

  9. Discovery space for indirect methods: Radial velocity Astrometry

  10. Routes to Earth-like planets?

  11. Other distance independent tracers? TRANSITS Technique proposed in 1952, HD 209458 detected in 2000.

  12. Transit photometry from space: Kepler

  13. Astrometry? Hard w/single apertures, but moving forward, ultimately to imaging. Keck LGS-AO image, can now achieve ~200 mas precision over short timescales. HST worse. ACS + Coronograph (HD 141569) Artist’s conception, TPF-C (coronograph).

  14. Think about interferometry?

  15. Aperture Diffraction Pattern

  16. Radio arrays can give mas precision (non-thermal):

  17. Palomar Testbed Interferometer (PTI)

  18. In the optical, difficult to maintain strict instrument stability, so use “dual star” astrometry. Large apertures are needed to get enough background stars nearby.

  19. Space Interferometry Mission (SIM)

  20. Nulling: Use the fringes to suppress the central star. First tests w/ Keck in 2007.

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