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Extrasolar planet detection: Methods and limits Ge/Ay133
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Spectral Energy Distributions (or, Blinded by the light!...)
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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?
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How do you find a planet? Look for it? Hard! Where should you look? Few AU? Look for its affect on the star? (Indirect)
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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
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Discovery space for indirect methods: Radial velocity Astrometry (r=distance to the star)
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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)..
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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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Discovery space for indirect methods: Radial velocity Astrometry
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Routes to Earth-like planets?
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Other distance independent tracers? TRANSITS Technique proposed in 1952, HD 209458 detected in 2000.
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Transit photometry from space: Kepler
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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)
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Think about interferometry?
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Aperture Diffraction Pattern
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Radio arrays can give as precision (non-thermal):
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Palomar Testbed Interferometer (PTI)
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In the optical, difficult to maintain strict instrument stability, so use “dual star” astrometry. Large apertures are needed to get enough background stars nearby.
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Space Interferometry Mission (SIM)
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Nulling: Use the fringes to suppress the central star. First tests w/ Keck in 2007.
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