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Maria Pia Di Mauro INAF- Istituto di Astrofisica Spaziale e Fisica Cosmica Rome (Italy)

HELIOSEISMOLOGY. Maria Pia Di Mauro INAF- Istituto di Astrofisica Spaziale e Fisica Cosmica Rome (Italy). The story. Periodic Motions P  5 min of the absorption lines of the photospheric spectrum (Leighton et al. 1962). PULSATIONS OF THE PHOTOSPHERE!!!. Normal Modes.

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Maria Pia Di Mauro INAF- Istituto di Astrofisica Spaziale e Fisica Cosmica Rome (Italy)

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  1. HELIOSEISMOLOGY Maria Pia Di MauroINAF- Istituto di Astrofisica Spaziale e Fisica Cosmica Rome (Italy) IHY Conference “The Sun, the Heliosphere, and the Earth” Bad Honnef, May 14-18 2007

  2. The story..... Periodic Motions P  5 min of the absorption lines of the photospheric spectrum (Leighton et al. 1962) PULSATIONS OF THE PHOTOSPHERE!!!

  3. Normal Modes Acoustic waves trapped in resonant cavities  p modes (Ulrich 1971, Leibacher & Stein 1972) Normal modes n radial order l harmonic degree mazimuthal order

  4. The proofDeubner 1975

  5. Patches of the solar surface oscillate up and down These data from the SOI/MDI instrument on board the SOHO satellite 1024x1024 points over visible disk 1-minute cadence or better One Million of indipendent modes excited. Each mode with a different tone!!

  6. Mode trapping Eigenfunction oscillates as function of r when

  7. Study of the solar oscillations observed at the surface to probe the structure and the dynamics of the Sun Study of oscillations in the Sun in a similar way as geoseismology is the study of earthquakes The technique is very similar to trying to determine the shape of musical instruments from the sound they make. Helioseismology

  8. Why helioseismology? • Frequencies depend on the structure of the star • r(r) , p(r) , G1(r) , c(r) • but only 2 independent functions:e.g.r(r) and c(r) • Frequencies can be measured with accuracy (10-5) • Basic physics addressed -Equation of state, opacities, neutrinos, general relativity, fluid dynamics • Stellar physics addressed -Stellar evolution, differential rotation, origin of solar magnetism, nature of spatial and temporal inhomogeneitities • Solar-terrestrial physics addressed -Origin of magnetic storms

  9. Global Helioseismology • Structure & dynamics of the longitudinally averaged solar interior & changes with time • Frequencies of p modes Helioseismic Methods • Local Helioseismology • Structure and dynamics of pieces of the solar interior & changes with time • Travel time of running sound waves

  10. Notable Successes of Helioseismology • Depth of the solar convection zone (Christensen-Dalsgaard 1985) • Opacity • Neutrino Problem • Diffusion of helium and heavy elements (Basu et al. 1996) • Helium abundance • Relativistic effect in the core (Elliot & Kosovichev 1998) • Internal Dynamics

  11. HELIOSEISMIC APPROACHES Forward approach Model Observables Inverse approach Aim of inversion: to make inferences about localized properties of the solar interior

  12. ACTUAL SOUND-SPEED DIFFERENCE SUN-MODEL S

  13. Turbulent diffusion Christensen-Dalsgaard & DiMauro 2007 in press

  14. Grevesse & Noels 1993 New solar surface abundances Asplund et al. (2004 A&A 417, 751) Improvements: • Non-LTE analysis • 3D atmosphere models Unfortunately this model has a too small CZ and lower He abundance than inferred one!! Montalban et al. 2004

  15. RELATIVE DENSITY DIFFERENCES SUN-MODEL S

  16. EQUATION OF STATE First adiabatic exponent 1 5/3 in the interior except in the H and He ionization zones • MHD (Mihalas, Däppen & Hummer 1990)- chemical picture • Pressure ionization (Partition equation) • NonRelativistic Electron degeneracy • Excited states • Coulomb correction in the Debye-Hückel approximation • OPAL (Rogers, Swenson & Iglesias 1996) - physical picture • Pressure ionization • Relativistic Electron degeneracy(OPAL2001) • Excited states Partition equation and degree of ionization • Coulomb correction (many-body quantum physics) • Electron exchange • Quantum diffraction

  17. EOS in the surface Difference between SUN and Model S MDI data l<1000

  18. HELIUM ABUNDANCE IN CZ • Y cannot be directly obtained by spectroscopy • Y by solar Models matching L Y  0.27-0.28 • Now: Helioseismic inversions

  19. Di Mauro et al. 1998 tachocline Internal Rotation Rotation breaks spherical simmetry of the Sun and splits the frequency of oscillations Howe et al. 2000 rc/R = 0.67 +/- 0.05 (Di Mauro et al 1997)

  20. Deviations from the mean rotation profile as a function of latitude and time Howe et al. 2000 The Solar Cycle • Activity grows and decays over 11 years • Zones of magnetic activity move towards the equator • Bands of slower and faster rotation also migrate, ahead of the magnetic bands

  21. TORSIONAL OSCILLATIONS MDI OLA 0.99 R 0.95 R 0.84 R 0.90 R Differences between inversions of data taken at successive times reveal the “torsional oscillation”

  22. Torsional oscillations of whole CZ Differencing rotation inversions at successive 72-day epochs relative to solar minimum (1996) shows equatorward and poleward migration of torsional oscillations Vorontsov et al. 2002 Science

  23. Tachocline Oscillations Howe 2006 The rotation rate appears to show quasi-periodic oscillations of 1.3 year period near the base of the convection zone at mid-latitudes

  24. ROTATION IN THE CORE • MDI l < 100(Schou et al. 1998)+ • IRIS l=1-3 (Lazreck et al. 1996; Gizon et al1997, Fossat 1998) • GONG l=1-3(Gavryuseva & Gavryuseva 1998) • BISON +LOWL l=1-4 (Chaplin et al. 1999) • GOLF l=1-2 (Corbard et al. 1998) Di Mauro et al. 1998

  25. News!!! 10 years of observations from GOLF Solar Gravity Modes detected with GOLF!!! Garcia et al. 2007 on Science last week Observed g mode is consistent with a model with a rotationrate 3 or 5 times higher than radiative interior

  26. Diffusion • Non adiabatic effects Improve model • Convection • Rotation • Magnetic fields • EOS • 2D model • Longer series of oscillations data • g modes Observations Conclusion

  27. PICARD CNES Launch: 2009 PREMOS (low l and g modes) to study of the Earth climate and Sun variabilityrelationship SO Solar OrbiterESA Launch: 2013 VIM (local helioseismology at high latitude)to study,by approaching as close as 45 solar radii, the polar regions and the side of the Sun not visible from Earth The future… SDO Solar Dynamics Observatory, HMI (local helioseismology)NASA launch: 2008 tounderstand variation of magnetic fields dynamical processes and solar structureand its impact on Earth DYNAMICS Dynamics and Magnetism from the Internal core to the Chromosphere of the Sun, Turck-Chieze et al. Saclay, (France) Launch:???

  28. European Helio and Asteroseismology Network Co-ordinated Action funded by FP6 the 6th Framework Programme of the European Union Objective:Bringing together the European research groups active in helio- & asteroseismology. Start date:April 1, 2006Duration:48 months Coordinator: Oskar von der Lühe, Kiepenheuer-Institut für Sonnenphysik, Freiburg More information http://www.helas-eu.org

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