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Extrasolar planet detection: Methods and limits Ge/Ay133.

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Presentation on theme: "Extrasolar planet detection: Methods and limits Ge/Ay133."— Presentation transcript:

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 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  as, as of 2007) 200  as

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: 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 (  5  m, good for late type stars and brown dwarfs). Keck

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11 Discovery space for indirect methods: Radial velocity Astrometry

12 Routes to Earth-like planets?

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

14 Transit photometry from space: Kepler

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

16 Think about interferometry?

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20 Aperture Diffraction Pattern

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24 Radio arrays can give  as precision (non-thermal):

25 Palomar Testbed Interferometer (PTI)

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

28 Space Interferometry Mission (SIM)

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

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