Maria pia di mauro inaf istituto di astrofisica spaziale e fisica cosmica rome italy
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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


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

The story
The story.....

Periodic Motions P  5 min

of the absorption lines of the photospheric spectrum

(Leighton et al. 1962)


Normal modes
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

The proof deubner 1975
The proofDeubner 1975

Patches of the solar surface oscillate up and down

These data from the

SOI/MDI instrument

on board the SOHO


1024x1024 points

over visible disk

1-minute cadence

or better

One Million of indipendent modes excited. Each mode with a different tone!!

Mode trapping
Mode trapping

Eigenfunction oscillates as function of r when

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.


Why helioseismology
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

Helioseismic methods

  • 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

Notable successes of helioseismology
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

Helioseismic approaches

Forward approach



Inverse approach

Aim of inversion: to make inferences about localized properties of the solar interior

Turbulent diffusion
Turbulent diffusion

Christensen-Dalsgaard & DiMauro 2007 in press

New solar surface abundances

Grevesse & Noels 1993

New solar surface abundances

Asplund et al. (2004 A&A 417, 751)


  • 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


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

Eos in the surface
EOS in the surface

Difference between SUN and Model S

MDI data l<1000

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

Internal rotation

Di Mauro et al. 1998


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)

The solar cycle

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

TORSIONAL OSCILLATIONS latitude and time Howe et al. 2000



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”

Torsional oscillations of whole cz
Torsional oscillations of whole CZ latitude and time Howe et al. 2000

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

Tachocline oscillations
Tachocline Oscillations latitude and time Howe et al. 2000

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

Rotation in the core
ROTATION IN THE CORE latitude and time Howe et al. 2000

  • 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

News!!! latitude and time Howe et al. 2000

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


  • Diffusion latitude and time Howe et al. 2000

  • Non adiabatic effects

Improve model

  • Convection

  • Rotation

  • Magnetic fields

  • EOS

  • 2D model

  • Longer series of oscillations data

  • g modes



The future

PICARD latitude and time Howe et al. 2000CNES 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:???

European helio and asteroseismology network
European Helio and Asteroseismology Network latitude and time Howe et al. 2000

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

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