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Introduction: Onset of solar flares and coronal mass ejections

Yokoyama, T.Dept. Earth & Planetary Science, University of Tokyo

Isobe, H. Univ. Tokyo

Shibata, K. Kyoto Univ.

AOGS 20062006. 7. 13 Singapore

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Observational evidence for the magnetic reconnection model

The “CSHKP” model

Masuda et al. (1994)

Shibata et al. (1995)

Tsuneta et al. (1992)

Yokoyama et al. (2000) see also Lin et al. (2005)

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Reconnection in the onset of a CME

Lin & Forbes (2000)

Chen & Shibata (2000)

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Observational evidence for the magnetic reconnection model

The “CSHKP” model

Masuda et al. (1994)

Shibata et al. (1995)

Tsuneta et al. (1992)

Yokoyama et al. (2000)

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What is the next ?

• Energy build-up and trigger mechanism of flares/CMEs

• Particle accelerations• Reconnection physics• and so on …

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Temporal change of the magnetic patterns on the surface:Complex motions ; shear, rotation, collision, emergence

The coronal field lines are twisted and sheared. Free energy is stored in a form of electric currents.

Release of the stored free magnetic energy

Energy build up

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Plasma eruption triggered by emerging flux

The helical field lines are ejected upward.

erupting field lines

Notoya, TY, HI et al. (2006)

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SOLAR-B/SOT

(SOHO/MDI NASA)

•3-componets vector field•High resolution (~0.2 arcsec)•Without interruption

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Topics in the following talks

• Measurement of the helicity and its injection in terms of the energy build-up in the corona

• Reconstruction of the coronal field from the observational data of the photospheric magnetic field.

• Energy build-up processes: shear & emergence of magnetic flux

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Questions

• How is the free magnetic energy stored ? Where and when ?

• What is the trigger mechanism of a flare/CME ?• How can we reconstruct the magnetic field in the

corona ? Is it OK only by using the photospheric field information ?

• Is the helicity (or helicity injection) a good parameter for the prediction of a flare/CME event ?

• What are the conditions of an active region to be flare/CME productive ?