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Courtney Dressing Advisor: David Charbonneau All Souls College, Oxford July 4, 2011

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Number of target stars: 156,453 (58,041) Number of candidates: 1,235 (438) ◦ Orbiting 997 (375) stars Solar Subset: T eff = K log g = Kepmag < 15 Bright Dwarf Sample: T eff = K

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Within each grid cell, calculate: ◦ Number of candidates ◦ “Augmented” number of candidates ◦ Number of stars searched ◦ Planet occurrence rate

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Number of non-transiting planets with same radius and period as transiting candidates =probability of transit where

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Number of stars for which each transiting planet has SNR > 10

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# of Stars Searched Augmented # of Planets Planet Occurrence Rate =

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Periods <50 days Radii: 2-32 R Earth

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Planet Radius 10 Days17 Days 2 R Earth 2.8 R Earth Period

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k R = /-0.4 α = ± 0.11

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Larger planets have shorter cutoff periods and sharper transitions.

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f 0 = 0.165±0.011 k T =-0.081±0.011

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Random errors? ◦ Trend preserved for T eff = K ◦ Trend preserved after Monte Carlo applying gaussian random deviates to T eff and log g Systematic stellar radius bias? ◦ Would require log g error of 1.6 dex ◦ Errors in KIC are ~0.25 dex Systematic metallicity bias? ◦ Errors on [Fe/H] in KIC are ≳0.2 dex (rms) ◦ Cannot be ruled out

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More massive planets have more H/He gas Change at 4.5 M E ? Models from Fortney et al Solar system Kepler Other surveys

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Assume planets with densities above 4 g/cm 3 are primarily composed of refractory elements

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Toy density models ◦ Constant density ◦ Piece-wise constant density Compared to Eta-Earth Survey ◦ Volume-limited survey of 166 GK dwarfs ◦ 35 planets detected around 24 stars ◦ Keck-HIRES ◦ See Howard et al. 2010

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Black: Kepler prediction Red: Eta-Earth measurement Decreasing density

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Best models have ρ≳4g/cm 3 for Rp≲3R E

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Planet occurrence increases with decreasing radius and increasing orbital period Smaller planets (2-4 R E ) are more common around cooler stars (metallicity effect?) Larger planets have steeper cutoffs at shorter periods than smaller planets There is a ridge of high planet occurrence from 3 days and 2 R E to 50 days and 4 R E.

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