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Investigating the structure of transiting planets, from hot Jupiters to Kepler super Earths

Investigating the structure of transiting planets, from hot Jupiters to Kepler super Earths. Jonathan Fortney University of California, Santa Cruz Thanks to: Neil Miller (UCSC) , Eric Lopez (UCSC) Eliza Miller-Ricci Kempton (UCSC), Nadine Nettelmann (U. of Rostock) . J. E.

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Investigating the structure of transiting planets, from hot Jupiters to Kepler super Earths

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  1. Investigating the structure of transiting planets, from hot Jupiters to Kepler super Earths • Jonathan Fortney • University of California, Santa Cruz • Thanks to: Neil Miller (UCSC) , Eric Lopez (UCSC) • Eliza Miller-Ricci Kempton (UCSC), Nadine Nettelmann (U. of Rostock)

  2. J E

  3. Transiting Planets, Large and Small • 115 planets have now been seen to transit their parent stars, with measured masses • 104 “hot Jupiters” • 5 “hot Neptunes” • 6 “super Earths” • Combination of planet radius and mass yield density --> composition • Strong bias towards finding mass/large planets on short-period orbits July 2007

  4. Radial Velocity Data To Yield Mass Transit Data To Yield Radius

  5. Our Gas Giant Prototypes: Jupiter and Saturn Fortney, Baraffe, & Militzer (2010) 5-25% Heavy Elements by Mass

  6. At Gyr ages, ~1.3 RJ is the largest radius of a standard cooling model Fortney et al. (2007)

  7. There is an incredibly diversity of worlds • We can also characterizethese planets, not just find them Late 2006 The shear number of discoveries opens up the prospect of understanding gas giants (Jupiter-like), ice giants (Neptune-like) and lower mass planets as classes of astrophysical objects

  8. Building a Model: Additional Interior Power Miller, Fortney, & Jackson (2009) 1 MJ planet with a 10 ME core, at 0.05 AU from the Sun

  9. Explaining Large Radii An area of active research!

  10. Beyond Radius Inflation: What are We Trying to Learn? • We’d like to understand giant planets as a class of astrophysical objects • What are their unifying properties?

  11. There is an emerging population of planets with no radius anomaly Miller & Fortney (2011), in press

  12. A strong correlation between star and planet abundances Miller & Fortney (2011), submitted See also, Guillot et al. (2006)

  13. A quasi-uniform super-solar enrichment above 0.5 MJ [Fe/H]<0.0 0.0≤[Fe/H]<0.2 0.2≤[Fe/H]<0.4 Miller & Fortney (2011), in press

  14. Implications for Giant Planets • Giant planets, as a class, are enriched in heavy elements • Enriched compared to the Sun • Enriched compared to their parent stars • Enrichment is a strong inverse function of mass, but with an apparent “floor” at high mass • Massive planets and low-mass brown dwarfs should have structural and atmospheric abundance differences Batygin et al. (2011) • The heavy element mass of an inflated planet could be estimated only from the planet’s mass and stellar metallicity • With that in hand, its additional interior power could be constrained • Radius inflation mechanism can be studied vs. orbital separation and planet mass

  15. Potential Future Investigations • Heavy element mass vs. stellar [Si/H], [O/H], [C/H] • Could be used to understand the composition of the materials that make up the heavy element masses • These compositions not well constrained in the solar system • Heavy element mass vs. for well-aligned and mis-aligned system • Could show the influence of environment and dynamical history on the accretion of heavy elements Gaudi & Winn (2006)

  16. There is an incredibly diversity of worlds • We can also characterizethese planets, not just find them

  17. The Kepler Mission • Monitoring 150,000 stars for 3.5+ years • 20 months into the mission • First 4 months is now public • 1200+ transiting planet candidates • d < 0.25 AU

  18. Howard et al. (2011) Analysis: 2-3 RE Most Common Size Analysis of first 4 months of data---much more still to come

  19. Borucki et al. (2011) Analysis: 2-3 RE Most Common Size

  20. Kepler-11 • The most densely-packed planetary system yet found • 5 planets within the orbit of Mercury • Masses obtained only from Transit Timing Variations, with no Stellar RV • Relatively low density for all planets implies thick H/He atmospheres

  21. Kepler-11: Picking out the Planets

  22. Kepler-11: Lightcurves and Transit Times

  23. Kepler-11: The Mass-Radius View GJ 1214b • Modeled as rock-iron cores with water or H/He envelopes • Atmospheric escape with time is ignored

  24. Atmospheric Gain and Loss CoRoT-7b Jackson et al. (2010) • In the Kepler-11 system, significantly more massive planets can be ruled out from stability considerations, particularly for the inner 2 planets Alibert et al. (2005)

  25. Conclusions • A batch of new discoveries show that “mini-Neptunes” are a very common type of planet • The processes that affect H2-dominated atmosphere gain/escape should be investigated in much more detail • The Kepler-11 system is a natural laboratory to study atmospheric mass loss • Planet types keep emerging that we have no analog for in the solar system • We can now begin to understand the structure of giant planets with lower-irradiation transiting planets • Kepler has already found a larger sample of these types of planets, but follow-up observations for masses must be done

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