Census of Exoplanets (w/ Doppler observations) NASA

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1 Planetary Dynamics in the Kepler Era Eric B. Ford UF Frontiers September 2, 2011 w/ results from UF students/postdocs (Althea Moorhead, Robert Morehead, Benjamin Nelson, Matthew Payne), Kepler Follow-Up Observation Group, Kepler Multi-body Working Group & Kepler Science Team

2 Census of Exoplanets (w/ Doppler observations) NASA

3 Multiple Planet Systems NASA a (AU) Wright et al. (2008)

4 Two Planet System Discovered by Doppler Technique (24 Sextans) Johnson et al. 2011

5 Uncertainty in Orbital Periods (24 Sextans) Keplerian N-Body Keplerian N-Body Johnson et al Histogram Histogram

6 Are Doppler Surveys missing 1:2 MMRs? RV signature of 1 eccentric planet (e<0.3) is very similar to 2 planets in a 1:2 MMR RV surveys show giant planets often have moderate eccentricities Could these really be due to pairs of planets with a mass ratio ~e? Typically >100 RVs needed to distinguish between models

7 NASA s Kepler Mission Photometry of >150,000 stars 50μmag in 6 hours; 30 minute cadence Looking for Earth-like planets in transit First ~120 days went public Feb 1, 2011 Next ~90 days goes public Sep 23, 2011 NASA

8 Kepler s First Light NASA

9 NASA

10 NASA

11 Numbers of multiples: 115 doubles, 45 triples, 8 quads, 1 of five & 1 of six! Borucki et al. 2011b Lissauer et al. 2011b

12 Fabrycky

13 Holman et al. 2010

14 Transit Timing: A New Method for Confirming & Characterizing Extrasolar Planets Holman et al. 2010

15 Fits to transit timing data Holman et al. 2010

16 Mutual Inclination of Kepler-9 b/c Constraint from the lack of duration changes, not from TTV. Holman et al. 2010

17 Many More Systems with Transit Timing Variations Ford et al. 2011

18 Why Kepler Planets Could be Different Lower planet masses: More tightly packed systems can be stable Mutual perturbations are weaker Migration histories Could be qualitatively different (planetessimal vs gaseous disk) Likely faster for smaller planets Easier to pass through or be ejected from MMR Precise powerful observational constraints Precise orbital period & phase TTVs

19 Examples of Candidate Multiply- Transiting Planetary Systems Lissauer b

20 Resonance Preference Lissauer b

21 Why are they near resonance? Perturbations from binaries/flybys? Rare(Boley, Payne in prep.) Perturbations of other planets Unlikely, due to masses needed (Chatterjee in prep.) Possible exception for 3-body resonances Scattered out of resonance? Disk Migration Might work if rapid migration But eventually the disk goes away Rapid Disk Dispersal? (Chatterjee, Payne in prep.) To be continued

22 Candidate Radius Comparison CDF of candidate radius ratio (outer/inner) Saturn/Jupiter is 0.84, Earth/Venus is Lissauer et al. 2011b

23 Hill spacing a i+1 m i+1 a i M * m i Hill stable All 115 two-planet candidate systems are Hill stable! Fabrycky; Lissauer b

24 Long-term stability Δ inner +Δ inner =18 Gray: 2-planet instability zones Fabrycky; Lissauer b

25 Long-term stability P out /P in =1.258 => Protected by 5:4MMR? Fabrycky; Lissauer b

26 Eccentricities & Inclinations Transit durations related to eccentricity distribution (& stellar densities) Frequency of multiply transiting systems related to inclination distribution

27 Transit Duration vs Planet Size Smaller sizes longer transit durations (strong caution about potential correlation with stellar properties; see Howard+ 2011) Moorhead+ 2011

28 Transit Duration vs Multiplicity Moorhead+ 2011

29 Inclination Distributions Lissauer b

30 Planet Multiplicity & Mutual Inclinations (σ) p(n;λ) = λ N exp(-λ) / N! (Poisson) p(i;σ) = i / σ 2 exp(-i 2 /2σ 2 ) (Rayleigh) (λ) Ragozzine

31 KOI-500 Observations (short-term) Nominal Model (long-term) Ford et al. 2011

32 Kepler, TTVs & the Habitable Zone Ford et al. 2011

33 Kepler Dynamics Papers Borucki et al. 2011b: Overview & table of planet candidates Holman et al. 2010: Kepler-9 b & c First system of multiple transiting planets. First planets confirmed by TTVs. Lissuaer et al. 2011a: Kepler-11 b-g System of six closely spaced planets. Five confirmed by TTVs Latham et al. 2011: Comparison of Stellar Properties of Singles & Multis Lissauer et al. 2011b: Dynamics of multiple planet systems Nearly all observed multis are stable Slight excess near, but likely not in resonance ~3% of stars have 3-4 planet systems with inclinations of ~2-5 degrees Moorhead et al. 2011: Distributions of Transit Durations & Eccentricities Similar or slightly less eccentric than more massive RV planets Hints of trends w/ size & multiplicity. Ford et al. 2011: TTV Statistics ~12% of systems show TTVs Many more multiple systems w/ TTVs expected during mission More accepted (~4), submitted (~2-5) or in preparation

34 Kepler, the Multiple-Transiting Planet Machine Tripled the sample of multi-planet systems Enables physical & orbital characterization Significance of resonances versus mass New architectures for low-mass planetary systems Multiple-transiting planets & transit timing variations (TTVs) probe orbital dynamics & planet formation TTVs can confirm planets transiting faint stars TTVs could confirm transiting HZ objects

35 Questions NASA