The Solar Interior and Helioseismology

Transcription

1 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

2

3

4

5

6

7

8 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

9 Four solar cycles with BiSON Chaplin & Basu, Space Science Reviews, 2014, 186, 437

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

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

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

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

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

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

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

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

18 GONG data Internal Solar Rotation

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

20 The Solar Activity Cycle

21 Resonance in simple 1-D pipes

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

23 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)

24 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)

25 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

26 Latitude Variations in Global Mode Damping and Energy Mode Damping Inference on changes to convection, which excites and damps modes Energy (forcing/damping) Komm, Howe & Hill, 2002

27 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

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

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

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

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

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

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

34 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

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

36 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

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

38 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

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

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

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

42 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

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

44 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

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

46 Kepler and CoRoT Exquisite quality photometric data

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

48 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)

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

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

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

52 ( 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

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

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

55 Surface rotation periods Kepler lightcurves of solar-type stars

56 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

57 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

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

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

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

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

62 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

63 End