The Solar Interior and Helioseismology

The Solar Interior and Helioseismology Bill Chaplin, School of Physics & Astronomy University of Birmingham, UK STFC Advanced Summer School, 2016 Sep 6 University of Sheffield

http://solarscience.msfc.nasa.gov/predict.shtml

Seismology as a probe of the solar cycle Bill Chaplin, School of Physics & Astronomy University of Birmingham, UK STFC Advanced Summer School, 2016 Sep 6 University of Sheffield

Four solar cycles with BiSON 21 22 23 24 Chaplin & Basu, Space Science Reviews, 2014, 186, 437

Acoustic signatures of the solar cycle: where it all started SMM/ACRIM data Woodard & Noyes 1985, Nature; 1988, IAU123

Clear correlations with surface measures of activity Elsworth et al. 1990, Nature, 345, 322

Frequency dependence at low degree Elsworth et al. 1994, ApJ, 434, 801

Frequency and degree dependence of shifts Libbrecht & Woodard 1990, Nature, 345, 779

Sound waves generated at top of Convection Zone... Convection Zone Radiative Interior Acoustic source Photosphere

The Resonant Sun The Sun resonates like a musical instrument...

Standing acoustic wave patterns... Internal acoustic ray paths Surface displacement: spherical harmonics red waves give blue waves give

Project onto spherical harmonics l: number of nodal lines m: number of azimuthal nodal lines

GONG data Internal Solar Rotation

The Tachocline ( speed slope ) Located just beneath base of convection zone Key for dynamo action! Courtesy P. H. Scherrer, SOI Stanford

The Solar Activity Cycle

Resonance in simple 1-D pipes

Changes in Mode Properties... Magnetic fields can act as agents of change: Directly, by action of Lorentz force Indirectly by changing stratification

Effects of near-surface activity on modes Depends on spherical harmonic of mode (l, m) (1,0) (1,1) (2,0) (2,1) (2,2) (3,0)

Effects of near-surface activity on modes Depends on spherical harmonic of mode (l, m) (3,1) (3,2) (3,3) (5,5) (10,5) (10,10)

Global Frequency Shifts in GONG data: as Function of Solar Latitude Spatial dependence correlates strongly with active regions Dependence of shifts on mode degree, l, and mode frequency, suggests near-surface effect Courtesy R. Howe

Latitude Variations in Global Mode Damping and Energy Mode Damping Inference on changes to convection, which excites and damps modes Energy (forcing/damping) 60 20-20 -60 1996 1997 1998 1999 2000 2001 1996 1997 1998 1999 2000 2001 Komm, Howe & Hill, 2002

Torsional oscillations of the whole convection zone Difference in successive 72-d rotation inversions of MDI data Migrating bands of flow penetrate interior! Courtesy S. Vorontsov and collaborators

Slow start to cycle 24 Near-surface flows: GONG, MDI, HMI Howe et al. (2013)

Dynamics: comparing solar minima MDI & GONG data: cycle 24 cycle 23 Antia & Basu (2010)

Tachocline oscillations GONG and MDI data Above tachocline Beneath tachocline Howe et al. 2011, JPCS

Structure: comparing solar minima BiSON frequencies: cycle 24 cycle 23

Sounding stellar activity cycles: Sun BiSON Sun-as-a-star data scaled 10.7-cm radio flux

Quasi-biennial variation After removal of 11-yr cycle signature Broomhall et al., 2012, ApJ, 420, 1405

Cycles 22, 23 and rise of 24 BiSON Sun-as-a-star data 22 23 24 High-frequency modes Intermediate-frequency modes Low-frequency modes scaled 10.7-cm radio flux scaled ISN

Standing acoustic wave patterns... Internal acoustic ray paths Surface displacement: spherical harmonics red waves give blue waves give

Frequency dependence of shifts Mode inertia and mode mass E nl M 1 V ξ 2 dv M nl / M 1 2 M nl v 2 nl 1 2 E nl M v 2 nl

Frequency dependence of shifts Chaplin et al. 2001, MNRAS, 324, 910

Frequency dependence of shifts E( nl ) : inertia an l=0 mode would have at frequency nl Q nl E nl / E( nl ) Chaplin et al. 2001, MNRAS, 324, 910

Frequency dependence of shifts UTP for radial modes (model S )

Frequency dependence of shifts nl ( ( nl E nl ) nl nl )

Frequency dependence of shifts 1 nl [ E nl / E (3000)] 1 Chaplin et al. 2001, MNRAS, 324, 910

Frequency dependence of shifts What do we expect for? Change confined close to surface (but in the interior): = 0 Change confined to photosphere (within one pressure scale height): = 3

Frequency dependence of shifts 0 2 Chaplin et al. 2001, MNRAS, 324, 910

Cycles 22, 23 and rise of 24 BiSON Sun-as-a-star data 22 23 24 High-frequency modes Intermediate-frequency modes Low-frequency modes scaled 10.7-cm radio flux scaled ISN

And now the fall of Cycle 24 High-frequency modes Intermediate-frequency modes Low-frequency modes

Kepler and CoRoT Exquisite quality photometric data

Luminosity ( Sun) Asteroseismology of solar-type stars and red giants CoRoT More than 1,000 red giants Surface temperature (degrees Kelvin)

Luminosity ( Sun) Asteroseismology of solar-like oscillators Kepler Approx. 700 solar-type stars Approx.16,000 red giants Over 100 planet-hosting stars Surface temperature (degrees Kelvin)

Rotation of main-sequence stars l=2,0 and 1 modes in Kepler target KIC 6106415 0 1 2 Nielsen et al., 2013, A&A, 568, L12

Rotation of main-sequence stars Dipole modes in two Kepler planet hosting stars Kepler-50 Kepler-65 Chaplin et al., 2013, ApJ, 766, 101

Internal rotation of a subgiant Core rotates five-times faster than surface Deheuvels et al., 2012, ApJ, 756, 19

( Hz) /2 (nhz) Internal rotation from Kepler sub-giants and low-luminosity red giants cores envelopes Teff (K) log g (dex) Deheuvels et al., 2014, A&A, 564, 27

Convection zone depth From acoustic glitches Kepler example: solar-type dwarf Signal present in particular combinations of frequencies Mazumdar et al., 2014, ApJ

Signatures of stellar activity Kepler lightcurves of solar-type stars Basri et al., 2011, ApJL, 713, 155

Surface rotation periods Kepler lightcurves of solar-type stars

F/F (ppm) Stellar cycles with Kepler? From variability of lightcurve: two F-type stars Time (days) Time (days) Mathur et al., 2014, A&A, 562, 124

The Sun amongst stars Selection of solar-type stars (Kepler) and the Sun (SOHO/VIRGO) Kepler stars Sun Gilliland, Chaplin et al., 2015, AJ, 150, 133

Age-rotation comparisons Garcia et al. 2014 A&A, 572, 34 Davies et al. 2014, MNRAS 446, 2959 do Nascimento Jr. et al. 2014, ApJ, 790, L23

CoRoT reveals a short activity cycle in HD49933 García et al., 2010, Science, 329, 1032

Kepler: solar-type stars with 3+ years of asteroseismic data KASC field stars Kepler Objects of Interest

Asteroseismic inference on distribution of near-surface activity (1,0) (1,1) (2,0) (2,1) (2,2) (3,0)

Inference: surface distribution of activity sizes and phases of frequency shifts depend on (l, m) Sun-as-a-star data max=40 ± 10 degrees Chaplin et al. 2007, MNRAS, 377, 17 Chaplin (2011), Proceedings Tenerife Winter School

End