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Inclination Distribution of Exoplanetary Systems

Inclination Distribution of Exoplanetary Systems. Darin Ragozzine (Harvard ITC Fellow), Kepler TTV/Multiples Working Group, & The Kepler Team. Extreme Solar Systems II Presentation 06.03 September 13, 2011.

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Inclination Distribution of Exoplanetary Systems

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  1. Inclination Distribution of Exoplanetary Systems Darin Ragozzine (Harvard ITC Fellow), Kepler TTV/Multiples Working Group, & The Kepler Team Extreme Solar Systems II Presentation 06.03 September 13, 2011

  2. Architecture of Kepler's Candidate Multiple Transiting Systems (Lissauer, Ragozzine, et al. 2011b) • Accepted paper on arXiv (v4, many minor updates)

  3. Multiple Transiting Systems [none pre-Kepler]

  4. Multiple Candidate Systems!!! Borucki et al. 2011, Lissuaer et al. 2011b, Ragozine & Holman 2010

  5. Multiple Candidate Systems!!! Borucki et al. 2011, Lissuaer et al. 2011b, Ragozine & Holman 2010

  6. Inclination Distribution Statistically • Inclination = True Mutual Inclination (Coplanarity) • Critical for planet formation/evolution theories • Compare frequency of different numbers of detected and non-detected planets • Correlated with multiplicity (# planets / star) - Itself interesting - Needed to convert average number of planets per star to fraction of star with planets (Youdin 2011) • Assume the majority can be described by particular multiplicity and inclination distribution functions

  7. Methods • Forward Model, match to Kepler observations • Alternative method by Tremaine & Dong 2011 • 1.5 < R < 6 RE, 3 < P < 125 days, ~all Kepler stars • (red = sim)

  8. 3-4 nearly coplanar planets Results 2-3 planets with large inclinations 4-5 coplanar planets

  9. Results • Some caveats/assumptions (see L11b) • Combining with other L11b results, we find: A few+ percent of stars have multiple (3-5), similar-sized, and nearly-coplanar 1.5-6 RE planets with periods between 3 and 125 days and period ratios that have a minor tendency to be just wide of resonance. • FSWP = NPS / Multiplicity (approx 0.05 = 0.2/4) • With the enhancement in Kepler detections reported yesterday, this goes up to ~5%.

  10. More Results from HARPS (Mayor et al. 2011) • ~50% of stars host at least 1 planet < 30 ME and Periods < 100 days • 70% of these are multiple!!! • Among the 10 most sampled stars are 29 planets! • Confirms that there is a prevalent population of multiple small-planet systems • Calculating RVs from my model shows that RV observations are independent of inclination but strongly dependent on true multiplicities

  11. HARPS vs. Kepler • When accounting for multiplicity, there is approximately an order of magnitude difference in the fraction of stars with planets measured by HARPS (~50%) and Kepler (~5%) • Possible contributors to this discrepancy • Residual Kepler incompleteness • Overestimated HARPS result (with errors, 50 +/- 17%) • KIC stellar parameters are inaccurate and/or biased • Fundamentally different kinds of stars • ...

  12. HARPS vs. Kepler • Possible contributors to this discrepancy • Statistical issues with binning/comparison... since the frequency increases so rapidly at the small end, small differences can lead to large apparent discrepancies • Imprecise or miscommunicated comparisons (e.g., Darin is confused/wrong) • Small planets generally have high densities (see Wolfgang & Laughlin, Gaidos et al. Posters, Howard et al. 2011). - Estimating the sin i correction and assigning all planets a density of 1 g/cc, then Kepler would find all of them - If all planets had a density of 5.5 g/cc, then the expected detectability for Kepler goes to ~25%

  13. Conclusions • Multi-transiting systems are awesome • Significant population of planetary systems with 3-5 nearly-coplanar planets - Inclination limits from Kepler frequencies • Disagreement between occurrence of systems between Kepler (~~5%) and HARPS (~~50%) • Treatment of multiplicity-inclination distribution in joint RV/transit survey will help break degeneracies and measure densities

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