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Travis Metcalfe (SSI) PowerPoint Presentation
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Travis Metcalfe (SSI)

Travis Metcalfe (SSI)

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Travis Metcalfe (SSI)

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  1. Asteroseismology of Kepler Exoplanet Host Stars Travis Metcalfe (SSI)

  2. 1992: first pulsar planets 3 planet system 2 = 4 x Earth mass 1 = 2 x Moon mass Orbits closer than Mercury

  3. 1995: first radial velocity planet 0.5 x Jupiter mass Orbit closer than Mercury

  4. 2001: first transiting planet Orbit closer than Mercury Size near Jupiter

  5. Exoplanet atmospheres Detections - Sodium - Carbon monoxide - Water vapour

  6. 2004: first microlensing planet Hosted by a tiny red dwarf Orbit size similar to Mars Mass similar to Jupiter

  7. 2008: first direct image Mass = 3 x Jupiter Orbit size = 3 x Neptune Host star mass = 2 x Sun

  8. Gliese 581g Mass = 3 x Earth Orbit size = 0.4 x Mercury Host star mass = 0.3 x Sun 2010: first habitable planet?

  9. Higher temperature = faster sound speed Lighter gases = faster sound speed

  10. Global oscillation properties nmax Elsworth & Thompson (2004)

  11. Mathur et al. (2012) Scaling relations

  12. Grid-based methods Mathur et al. (2012)

  13. Fitting the frequencies Metcalfe et al. (2012)

  14. Chaplin et al. (2011, Science) Asteroseismic Modeling Portal http://amp.ucar.edu/ • Stellar evolution tracks from ASTEC, pulsation analysis with ADIPLS • Parallel genetic algorithm optimizes globally, local analysis + SVD for errors • Stellar age from match to large separation, correct surface effects empirically 0.75 < M< 1.75 0.002 < Z< 0.05 0.22 < Y< 0.32 1.0 <a< 3.0 Metcalfe et al. (2009), Woitaszek et al. (2009)

  15. Kepler-21: a love story • 1.64±0.04 Re planet in a 2.8-day orbit around an oscillating F subgiant • Asteroseismic target prior to exoplanet discovery, expanded collaboration • radius (1.86±0.04 R), mass (1.34±0.06 M), age (2.84±0.34 Gyr) Howell et al. (2012)

  16. Kepler-22: habitable super-Earth • 2.38±0.13 Re planet with 290-d orbit in habitable zone of G5 host star • Spectroscopy and global oscillation properties for grid-based modeling • radius (0.98±0.02 R), mass (0.97±0.06 M), age (~4 Gyr?) Borucki et al. (2012)

  17. Kepler-36: formation puzzle Carter et al. (2012, Science)

  18. Kepler-36: formation puzzle • 1.5 and 3.7 Re planets in 13.8-d and 16.2-d orbits (7:6 period ratio) • Asteroseismology and transit timing variations yield planet densities • Super-Earth and Neptune (8:1 density ratio) in neighboring orbits. How? Carter et al. (2012, Science)

  19. Kepler-##: smallest exoplanet • 0.28 / 0.8 / 2.1 Re planets in 13 / 21 / 39 day orbits (no TTVs yet detected) • radius (0.77±0.02 R), mass (0.80±0.04 M), age (~6 Gyr) • Innermost planet is smaller than Mercury (similar to size of Moon) Barclay et al. (submitted)

  20. Future prospects • Longer data sets will resolve mode splitting, providing independent constraints on rotational inclination and spin-orbit alignment. • Extended time series will probe variations due to magnetic cycles, and provide statistics on stellar super-flares (with implications for habitability). • Comparison with control sample of stars without known planets may reveal correlations between stellar composition and occurrence of planets.