ragozzine - essii inclination distribution of exoplanetary systems extreme solar systems ii...
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Ragozzine - ESSII
Inclination Distribution of Exoplanetary Systems
Extreme Solar Systems IIPresentation 06.03
September 13, 2011
Darin Ragozzine (Harvard ITC Fellow), Kepler TTV/Multiples Working Group,
& The Kepler Team
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Architecture of Kepler's Candidate Multiple Transiting Systems (Lissauer, Ragozzine, et al.
2011b)
• Accepted paper on arXiv (v4, many minor updates)
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Multiple Transiting Systems
[none pre-Kepler]
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Multiple Candidate Systems!!!
Borucki et al. 2011, Lissuaer et al. 2011b, Ragozine & Holman 2010
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Multiple Candidate Systems!!!
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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
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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)
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Results
2-3 planets with large inclinations
4-5 coplanar planets
3-4 nearly coplanar planets
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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%.
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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
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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 ...
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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%
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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