travis metcalfe (ssi)
DESCRIPTION
Asteroseismology of Kepler Exoplanet Host Stars. Travis Metcalfe (SSI). 1992: first pulsar planets. 3 planet system 2 = 4 x Earth mass 1 = 2 x Moon mass Orbits closer than Mercury. 1995: first radial velocity planet. 0.5 x Jupiter mass Orbit closer than Mercury. - PowerPoint PPT PresentationTRANSCRIPT
Travis Metcalfe (SSI)
Asteroseismology of Kepler Exoplanet Host Stars
1992: first pulsar planets
3 planet system
2 = 4 x Earth mass
1 = 2 x Moon mass
Orbits closer than Mercury
1995: first radial velocity planet
0.5 x Jupiter mass
Orbit closer than Mercury
2001: first transiting planetOrbit closer than Mercury
Size near Jupiter
Exoplanet atmospheres
Detections
- Sodium
- Carbon monoxide
- Water vapour
2004: first microlensing planet
Hosted by a tiny red dwarf
Orbit size similar to Mars
Mass similar to Jupiter
Mass = 3 x Jupiter
Orbit size = 3 x Neptune
Host star mass = 2 x Sun
2008: first direct image
2010: first habitable planet?
Gliese 581g
Mass = 3 x Earth
Orbit size = 0.4 x Mercury
Host star mass = 0.3 x Sun
Higher temperature = faster sound speed
Lighter gases = faster sound speed
Global oscillation properties
Elsworth & Thompson (2004)
max
Scaling relations
Mathur et al. (2012)
Grid-based methods
Mathur et al. (2012)
Fitting the frequencies
Metcalfe et al. (2012)
• 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 < < 3.0
Metcalfe et al. (2009), Woitaszek et al. (2009)
http://amp.ucar.edu/
Chaplin et al. (2011, Science)
Asteroseismic Modeling Portal
Kepler-21: a love story
Howell et al. (2012)
• 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)
Kepler-22: habitable super-Earth
Borucki et al. (2012)
• 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?)
Kepler-36: formation puzzle
Carter et al. (2012, Science)
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)
Kepler-##: smallest exoplanet
Barclay et al. (submitted)
• 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)
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.