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Exoplanet- Asteroseismology Synergies Bill Chaplin, School of Physics & Astronomy University of Birmingham, UK EAHS2012, Oxford, 2012 March 15
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Credit: IAC
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Oscillations as clocks: FM stars Shibahashi & Kurtz (2012), MNRAS, submitted (arXiv:1202.0105)
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Oscillations as clocks: V391 Peg Silvotti et al. (2007), Nature, 449, 189
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Pulsations in the HR diagram Aerts, Christensen-Dalsgaard & Kurtz 2009
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O-C diagram, prominent oscillation frequencies of V391 Peg Silvotti et al. (2007), Nature, 449, 189 Frequency #1Frequency #2
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Understanding stellar systems like our own…
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Jupiter: 1% area of the Sun (1/100 or 10,000 ppm) Earth or Venus: 0.01% area of the Sun (1/10,000 or 100 ppm) Photometry to detect transits
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Evolution and properties of stellar systems Precise, accurate fundamental stellar properties for modelling exoplanet systems: Seismic densities, radii, masses, ages Seismic log(g) for “boot strapping” spectroscopic analysis
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Internal rotation, stellar angle of inclination: Constraints on dynamical histories of stellar systems Evolution and properties of stellar systems
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Intrinsic activity, variability of host stars, influence on local environment: “Sound” stellar activity cycles Depths of convective envelopes, tests of stellar dynamos Evolution and properties of stellar systems
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asteroFLAG Hare and Hounds How Kepler would see Sun at v = 10
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asteroFLAG Hare and Hounds Stello, Chaplin et al. 2009, ApJ
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asteroFLAG Hare and Hounds
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Asteroseismic ensemble tests Kepler Input Catalogue Finds an underestimation bias in KIC radii Verner et al., 2011, ApJ, 738, L28 KIC – seismic log g (dex) KIC – seismic radii (%)
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Inferences on stellar activity, stellar cycles, activity of the “Sun in time”
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Sun (SOHO/VIRGO) Kepler: G type dwarf
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Sun (SOHO/VIRGO)
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Frequency spectrum of Cyg Solar-like oscillations Granulation Activity Guzik et al. (2012), in preparation
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Stellar activity suppresses oscillations Inference on magnetic fields and convection Detected oscillations?noyes Proxy for “stellar activity” Chaplin et al., 2011, ApJ, 732, 5L T eff (K)
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Frequency spectra of 16 Cyg A & B Metcalfe et al. (2012), ApJ
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Broomhall et al., 2009, ApJ, 700, L162 “Sounding” stellar activity cycles: Sun
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Broomhall et al., 2012, ApJ, 420, 1405 Quasi-biennial variation After removal of 11-yr cycle signature
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CoRoT reveals a short activity cycle in HD49933 García et al., 2010, Science, 329, 1032
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One example from the seismic Zoo Oscillation amplitudes Oscillation frequencies Light curve Variation of seismic frequencies and amplitudes Courtesy Salabert (Elsworth et al., work in progress)
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Inference on distribution: From frequency shifts of different modes From frequency asymmetry of components of non-radial modes Inference: surface distribution of activity sizes and phases of frequency shifts depend on ( l, m) Chaplin (2011), Proceedings Tenerife Winter School
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Activity distribution: non homogeneous, preferred bands of latitude Response of modes: depends on ( l, m) Inference: surface distribution of activity sizes and phases of frequency shifts depend on ( l, m) Chaplin (2011), Proceedings Tenerife Winter School
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Effects of near-surface activity on modes Depends on spherical harmonic of mode ( l, m) (1,0)(1,1)(2,0) (3,0)(2,2) (2,1)
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Chaplin et al. 2007, MNRAS, 377, 17 Spatial dependence of the frequency shifts Inference on active latitudes Predicted shifts simple model for latitudinal distribution surface activity Match to observed ratios
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Chaplin et al. 2007, MNRAS, 377, 17 Spatial dependence of the frequency shifts Inference on active latitudes Predicted shifts simple model for latitudinal distribution surface activity Match to observed ratios
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Chaplin et al. 2007, MNRAS, 377, 17 Spatial dependence of the frequency shifts Inference on active latitudes Predicted shifts simple model for latitudinal distribution surface activity Match to observed ratios
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Chaplin et al. 2007, MNRAS, 377, 17 Spatial dependence of the frequency shifts Inference on active latitudes Predicted shifts simple model for latitudinal distribution surface activity Match to observed ratios
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Inference: surface distribution of activity sizes and phases of frequency shifts depend on ( l, m ) Chaplin (2011), Proceedings Tenerife Winter School Sun-as-a-star data max =40 ± 10 degrees
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Stellar activity squashes mode peaks! 3.0 0.15 = 0.0 1.5 0.4 See Chaplin et al., 2008, MNRAS, 384, 1668
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Credit: IAC Asteroseismic analysis Kepler Objects of Interest (KOIs)
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Seismology of exoplanet host stars HAT-P-7 Christensen-Dalsgaard et al. 2010 Kepler-10b Batalha et al. 2011
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Howell et al. (2012), ApJ, 746, 123 Kepler 21b 1.6R E planet orbiting bright F-type sub-giant
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Brightest Kepler exoplanet host star High-precision stellar properties from asteroseismology: Stellar radius to 2.2% Stellar mass to 4.5% Stellar age to 12% Planetary radius to 2.4% Kepler 21b 1.6R E planet orbiting bright F-type sub-giant
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Kepler 22b 2.4R E planet in habitable zone of Sun-like star Borucki et al. (2012), ApJ, 745, 120 Strong signature of large frequency separation
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Inclination affects mode visibility (1,0)(1,1)(2,0) (3,0)(2,2) (2,1)
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Inclination affects mode visibility Gizon & Solanki, 2003, ApJ, 589, 1009 m=1m=1 0+1 m=2m=2 0 11 +2 l =1 l =2
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Inference on stellar inclination Height ratios depend on angle 2 yrs
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1 month Need long datasets Inference on stellar inclination
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Fin
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