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Ge/Ay133 What (exo)-planetary science can be done with transits and microlensing?
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A Jupiter transit across the Sun is ~1%: Curvature?
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Limb Darkening and Transit Profiles: Probes composition of atmosphere at day-night terminator Can search for clouds, hazes, condensates HST STIS transits of HD 209458b from 290-1030 nm (Knutson et al. 2007a) Atmosphere Star Planet
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Sometimes the absence of signal is interesting: No transits in 47 Tuc, `expectation’=30-40 (34,000 stars) Gilliland, R.L. et al. 2000, ApJ, 545, L47
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Transits, approach #1: Search for transits in systems known to have planets at the doppler crossings. Sato, B. et al. 2005, ApJ, astro-ph/0507009
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Transits and the Rossiter-McLaughlin effect (1924): Winn, J.N. et al. 2005, ApJ, 631, 1215
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Photometry can be straightforward: Amateur observations of HD 209458 b Bruce L. Gary, Santa Barbara, CA Arto Oksanen SBIG cameras, Meade telescopes, V filters
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Transits, approach #2: Search for transits in many stars using a suite of low cost robotic telescopes. TrES-1 Alonso, R. et al. 2004, ApJ, 613, L153
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Photometry from space can be extremely good: HD 209458 - HST The KEPLER mission is dedicated to photometry and can search for earth mass planets in the so- called habitable zone. Brown, T.M. et al. 2001, ApJ, 552, 699 www.kepler.arc.nasa.gov 95 Mpixel camera, 115 deg 2 FOV, 4’’ pixels
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But ground-based work is making strides! HD 209458 - HST At this level of performance (0.47 milli-mag) the transits of hot Neptunes are detectable & transit timing can put stringent limits on perturbing planets into the Earth mass range. Brown, T.M. et al. 2001, ApJ, 552, 699
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Secondary eclipses can also put limits on the visible albedo. The MOST satellite finds A(HD209458b)<0.25 (1 ) (Jupiter=0.5, 300-700 nm). Why so dark? Rowe, J.F.. et al. 2006, ApJ, 646, 1241
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Transit photometry from space: Kepler
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A comparison of transiting planet systems: As we’ll see, size is not a strong function of mass, so very accurate measurements are needed!
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T = 1060 ± 50 K A = 0.31 ± 0.14 Secondary ecplises in the IR with Spitzer, see photons from the hot Jupiters! Charbonneau, D. et al. 2005, ApJ, 626, 523
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T = 1060 ± 50 K A = 0.31 ± 0.14 Charbonneau, D. et al. 2005, ApJ, 626, 523 Rapid Pace of Spitzer Transit Results: HD 189733b Mapping the temperature variation of a hot Jupiter… T(max)~1200 K, T(min)~970 K Hot spot ~30 ± 10° from the sub- stellar point Bond albedo~0.30 Must be reasonably efficient circulation from day to night side.
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Other routes to Earth-like planets?
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Microlensing example:
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Are there Earth-like planets beyond the snow-line?
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Rapid Progress: Transiting Planets, 1 May 2007
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One year later (2008): 43 Systems And Counting Ice/Rock Planets
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HD 149026
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Other Correlations: Why would the mass/gravity of a close-in planet be tied to the period? May be some tie to the mass of the star… B. Hansen & T. Barman 2007, ApJ, 671, 61
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Other Correlations II: For a given T eq (not strictly distance since the spectral type varies…), two classes of planets versus Safronov number? B. Hansen & T. Barman 2007, ApJ, 671, 61
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Seems also to be tied to the mass of the planets: Selection bias or poor stellar radii? X Redistribution of energy? More next time… Evaporation? X (if “hot start”) Tidal heating? Planetesimals & migration (tie to Safronov #)? Need composition(s)! B. Hansen & T. Barman 2007, ApJ, 671, 61
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