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

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

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

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

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

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

Chaplin & Basu, Space Science Reviews,

2014, 186, 437

23 22 21 24

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

Photosphere

Acoustic source

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

Internal Solar Rotation

GONG data

The Tachocline (‘speed slope’)

Courtesy P. H. Scherrer, SOI Stanford

Located just

beneath base of

convection zone

Key for dynamo

action!

The Solar Activity Cycle

Resonance in simple 1-D pipes

Directly, by action of Lorentz force

Indirectly by changing stratification

Changes in Mode Properties...

Magnetic fields can act as

agents of change:

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)

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

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

(10,10) (10,5) (5,5)

Global Frequency Shifts in GONG

data: as Function of Solar Latitude

Courtesy R. Howe

Spatial dependence

correlates strongly

with active regions

Dependence of

shifts on mode

degree, l, and mode

frequency, suggests

near-surface effect

Variations in Global

Mode Damping and

Energy

La

titu

de

1996 1997 1998 1999 2000 2001 1996 1997 1998 1999 2000 2001

60

20

-20

-60

Energy (forcing/damping) Mode Damping

Komm, Howe & Hill, 2002

Inference on changes to

convection, which excites

and damps modes

Torsional oscillations of

the whole convection

zone

Difference in

successive 72-d

rotation inversions of

MDI data

Courtesy S. Vorontsov and collaborators

Migrating bands of flow penetrate interior!

Slow start to cycle 24

Howe et al. (2013)

Near-surface flows: GONG, MDI, HMI

Dynamics: comparing solar minima

Antia & Basu (2010)

MDI & GONG data: cycle 24 – cycle 23

Tachocline oscillations

Howe et al. 2011, JPCS

GONG and MDI data

Above

tachocline

Beneath

tachocline

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

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

Quasi-biennial

variation

After removal of

11-yr cycle

signature

Cycles 22, 23… and rise of 24 BiSON Sun-as-a-star data

High-frequency

modes

Intermediate-frequency

modes

Low-frequency

modes

scaled 10.7-cm radio flux scaled ISN

22 23 24

Standing acoustic wave

patterns...

Internal acoustic

ray paths

Surface displacement:

spherical harmonics

red waves give…

blue waves give…

MMdVME nlV

nl /ξ2

1

22

2

1

2

1nlnlnlnl vMEvM

Frequency dependence of shifts

Mode inertia and mode mass

Frequency dependence

of shifts

Chaplin et al. 2001, MNRAS, 324, 910

Chaplin et al. 2001, MNRAS, 324, 910

Frequency dependence of shifts

)(/ nlnlnl EEQ

: inertia an l=0 mode would have at frequency nl )( nlE

Frequency dependence of shifts

UTP for radial modes (model ‘S’)

nl

nlnl

E

)(

Frequency dependence of shifts

nl

nl

)(

Chaplin et al. 2001, MNRAS, 324, 910

11)]3000(/[

EEnlnl

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

Chaplin et al. 2001, MNRAS, 324, 910

0 2

Frequency dependence of shifts

Cycles 22, 23… and rise of 24 BiSON Sun-as-a-star data

High-frequency

modes

Intermediate-frequency

modes

Low-frequency

modes

scaled 10.7-cm radio flux scaled ISN

22 23 24

And now the fall of Cycle 24…

High-frequency

modes

Intermediate-frequency

modes

Low-frequency

modes

Kepler and CoRoT Exquisite quality photometric data

Surface temperature (degrees Kelvin)

Lum

inosity ( S

un)

Asteroseismology

of solar-type stars

and red giants

CoRoT

More than 1,000 red giants

Surface temperature (degrees Kelvin)

Lum

inosity ( S

un)

Approx. 700 solar-type stars

Approx.16,000 red giants

Over 100 planet-hosting stars

Asteroseismology

of solar-like

oscillators

Kepler

Nielsen et al., 2013, A&A, 568, L12

Rotation of main-sequence stars l=2,0 and 1 modes in Kepler target KIC 6106415

2

0 1

Chaplin et al., 2013, ApJ, 766, 101

Rotation of main-sequence stars Dipole modes in two Kepler planet hosting stars

Kepler-50 Kepler-65

Internal rotation of a subgiant Core rotates five-times faster than surface

Deheuvels et al., 2012, ApJ, 756, 19

Internal rotation from Kepler

Deheuvels et al., 2014, A&A, 564, 27

envelopes

cores

/2 (

nH

z)

log g (dex) Teff (K)

(

Hz)

sub-giants and low-luminosity red giants

Convection

zone depth

Mazumdar et al., 2014, ApJ

From “acoustic glitches”

Kepler example:

solar-type dwarf

Signal present in

particular combinations

of frequencies

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

Stellar cycles with Kepler? From variability of lightcurve: two F-type stars

Mathur et al., 2014, A&A, 562, 124

Time (days)

Time (days)

F

/F (

ppm

)

The Sun amongst stars

Gilliland, Chaplin et al., 2015, AJ, 150, 133

Kepler stars

Sun

Selection of solar-type stars (Kepler) and

the Sun (SOHO/VIRGO)

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

Kepler Objects of Interest

KASC field stars

Asteroseismic inference on

distribution of near-surface activity

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

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

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

Chaplin et al. 2007, MNRAS, 377, 17

End