Exoplanet-Asteroseismology

Synergies

Bill Chaplin, School of Physics & Astronomy University of Birmingham, UK

EAHS2012, Oxford, 2012 March 15

Oscillations as clocks: FM stars

Shibahashi & Kurtz (2012), MNRAS, submitted (arXiv:1202.0105)

Oscillations as clocks: V391 Peg

Silvotti et al. (2007), Nature, 449, 189

O-C diagram, prominent oscillation frequencies of V391 Peg

Silvotti et al. (2007), Nature, 449, 189

Frequency #1 Frequency #2

Understanding stellar systems like our own…

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

Internal rotation, stellar angle of inclination:­Constraints on dynamical histories of stellar

systems

Evolution and properties of stellar systems

Intrinsic activity, variability of host stars, influence on local environment:­ “Sound” stellar activity cycles­Depths of convective envelopes, tests of

stellar dynamos

Evolution and properties of stellar systems

asteroFLAG Hare and Hounds

Stello, Chaplin et al. 2009, ApJ

asteroFLAG Hare and Hounds

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 (%)

Inferences on stellar activity, stellar cycles, activity of the “Sun in time”

Sun (SOHO/VIRGO)

Kepler: Gtype dwarf

Sun (SOHO/VIRGO)

Frequency spectrum of Cyg

Solar-like oscillations

Granulation

Activity

Guzik et al. (2012), in preparation

Stellar activity suppresses oscillationsInference on magnetic fields and convection

Detected oscillations? noyes

Pro

xy fo

r “s

tella

r ac

tivity

”

Chaplin et al., 2011, ApJ, 732, 5L

Teff (K)

Broomhall et al., 2009, ApJ, 700, L162

“Sounding” stellar activity cycles: Sun

Broomhall et al., 2012, ApJ, 420, 1405

Quasi-biennial variationAfter removal of 11-yr cycle signature

CoRoT reveals a short activity cycle in HD49933

García et al., 2010, Science, 329, 1032

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)

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

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

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)

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

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

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

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

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

Stellar activity squashes mode peaks!

3.0

0.15

= 0.0

1.50.4

See Chaplin et al., 2008, MNRAS, 384, 1668

Credit: IAC

Asteroseismic analysis

Kepler Objects of Interest

(KOIs)

Seismology of exoplanet host stars

HAT-P-7 Christensen-Dalsgaard et al. 2010

Kepler-10b Batalha et al. 2011

Howell et al. (2012), ApJ, 746, 123

Kepler 21b 1.6RE planet orbiting bright F-type sub-giant

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 1.6RE planet orbiting bright F-type sub-giant

Kepler 22b 2.4RE planet in habitable zone of Sun-like star

Borucki et al. (2012), ApJ, 745, 120

Strong signature of large frequency

separation

Inclination affects mode visibility

(1,0) (1,1) (2,0)

(3,0)(2,2)(2,1)

Inclination affects mode visibility

Gizon & Solanki, 2003, ApJ, 589, 1009

m=1 0 +1 m=2 0 +11 +2

l =1 l =2

Inference on stellar inclination

Height ratios depend on

angle

2 yrs

1 month Need long datasets

Inference on stellar inclination

Fin