The Sun Through the Eyes of SOHO

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Solar Dynamo
Solar Cycle Spot Distribution
Emerging Active Regions
Solar Wind
Transient Events
Coronal Diagnostics and Modelling
Whats next?
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• Dynamo Theory of Solar Activity
• MHD investigation of dynamo mechanisms operating
  inside the Sun and late-type main sequence stars
• Spherical spectral MHD kinematic dynamo code
  developed
• at INAF-OACt (CTDYN)
• Including meridional circulation and
  sub-photospheric
• velocity fields deduced from helioseismology

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Recent results

• Solar dynamo models consistent with
• helioseismological data and
• observations of UV tracers motions
• A new dynamo mechanism, rising
• from the meridional circulation
• Consistent with observational data
• butterfly diagram,
• magnetic helicity,
• activity cycle intensity and period
  
  

Bonanno et al., AN, 2005, 2006
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Structure and Evolution of the Butterfly
Diagram Cycles 20, 21 22

• Maunders BD is a graphical representation of
  the
  spotgroups time-latitude distribution during the
  solar cycle
• Sunspot data obtained at Catania Astrophysical
  Observatory
• Years 1964 2003
• Unexpected features of the BD fine structure
  evidenced when a running window technique has
  been used to smooth data and reduce the noise

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Ternullo 2007. Solar Phys.
Equatorward migration of the spot zone halted
several times by stationary and even poleward
phases -- Spotted area oscillates during the
cycle?
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Active Region emergence D. Spadaro1, P. Romano1,
F. Zuccarello2 V. Battiato1, L. Contarino1, S.
Guglielmino2 1 OACt 2UCT

• SCIENTIFIC CONTEXT Why are the solar and
  stellar magnetic fields concentrated in
  relatively small areas of high field strength?
  Why do some of these field concentrations live
  for long time while others disappear after few
  hours/days ?
• OBSERVATIONS Coordinated observational
  campaigns between ground-based (THEMIS/IPM
  DST/IBIS INAF-OACt) and satellite instruments
  (TRACE SOHO/MDI SOHO/EIT HINODE)
• THEORY Model of a rising flux tube through the
  convection zone (NIRVANA)

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Results

• Common Results
• AR appearance firstly in the uppermost
  atmospheric layers and about 6-7 hours later in
  the inner atmospheric layers
• AFSs show an upward motion at their tops and a
  downward motion at their extremities
• The upward and downward motions decrease as the
  active regions evolve
• We observed some flow asymmetries between the
  preceding and the following sides of active
  regions
• Differences
• Different time interval between the appearance in
  chromosphere and photosphere ( 8 hours for the
  LL, simultaneous for the SL)
• Different order of magnitude of the magnetic flux
  increase (O1 in LL,
  2x in SL)
• Different direction of the motion of the two
  magnetic polarities (westward in SL)
• Higher plasma downflows measured in the f-side
  for the LL, in the p-side for the SL

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Flares and eruptive phenomena D. Spadaro1, P.
Romano1, F. Zuccarello2 V. Battiato1, L.
Contarino1, S. Guglielmino2 1 OACt 2UCT

• SCIENTIFIC CONTEXT What is the magnetic
  configuration in the pre-flare phase ? Why is the
  energy released ? How the complex magnetic
  configuration becomes unstable and the flare is
  triggered ? Where is the energy released? What
  happens after the energy is released ?
• OBSERVATIONS Coordinated observational
  campaigns between ground-based (THEMIS/IPM
  DST/IBIS INAF-OACt) and satellite instruments
  (TRACE SOHO/MDI SOHO/EIT HINODE)
• THEORY Study of the magnetic helicity
  transport in the corona

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• RESULTS
• Observational evidences that magnetic
  reconnection can occur between pre-existing
  coronal magnetic arcades and new emerging
  magnetic flux tube
• Reconnection observed in the loops of a coronal
  arcade as filaments rise through external layers
• Cancelling magnetic features can destabilize the
  equilibrium of a filament (surges and
  desappearance).
• Frequently multi-reconnection process can be
  caused by two different mechanisms at work
• Magnetic flux emergence
• Horizontal displacements of photospheric
  footpoints.

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Solaire Solar Atmospheric and interplanetary
Research
Solaire is

• A Research Training Network approved and
• financed by the European Commission under
• Framework Programme 6
• Duration of the network Jun 2007 May 2011
• 1. Instituto de Astrofisica de Canarias, Spain
  (P.I. Coordinator)
• 2. University of St Andrews, UK
• 3. Katholieke Universiteit Leuven, Belgium
• 4. Niels Bohr Institute, University of
  Copenhagen, Denmark
• 5. Max-Planck Institut für Sonnensystemforschung
  , Germany
• 6. Universitetet i Oslo, Norway
• 7. Observatoire de Paris Meudon, France
• 8. Ruhr-Universität Bochum, Germany
• 9. University of Glasgow, UK
• 10. Università di Catania, Italy
• 11. Utrecht University, The Netherlands
• 12. Eötvös University Budapest, Hungary
• 13. Fluid Gravity Engineering Ltd, United Kingdom

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• Structure and dynamics of the solar transition
  region (1)
• analysis of space observations from different
  instruments on board SOHO
• SUMER, CDS, EIT

SUMER quiet Sun observations
O VI 1032 Å
TR not a continuous transition between
the chromosphere and the corona
Basic components (building blocks) fine-scale,
variable magnetic structures

• Identification of photospheric footpoints
• Sánchez Almeida, Teriaca, Spadaro, et al.
  AA, 2007

• Chemical composition photospheric, with
• small variations from region to region
• Lanzafame et al. AA, 2005 Lang et al. AA,
  2007

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• Structure and dynamics of the solar transition
  region (2)
• Hydrodynamic modelling of small, cool loops
  undergoing transient heating
• (nanoflare-level), localized near the
  footpoints
• Spectral synthesis of TR line profiles
  (Spadaro, Lanza et al. ApJ, 2006)
• Characteristic behaviour of the observed quiet
  Sun TR well reproduced!

1986, Sol. Phys
Peter Judge ApJ, 1999
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Spectroscopic diagnostics of the extended solar
corona structure and dynamics solar wind source
regions
Determining the physical conditions of the
coronal plasma inside both open and closed
magnetic structures where the fast and slow solar
wind, respectively, originate, as well as those
of the regions in between is one of the most
crucial point in the solar wind and coronal
heating investigations.
EUV emission line observations provide a rich
and varied source of diagnostic information about
the solar corona from which empirical models can
be constructed based on numerical codes
synthesizing the intensities and profiles of the
spectral lines of interest.
UVCS/SOHO ultraviolet spectroscopic measurements
performed mostly during coordinated observations
of different instruments on board SOHO and on
different phases of the solar cycle have been
analyzed with the aim of providing the
constraints needed to test and guide theoretical
models of coronal heating and solar wind
acceleration.
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Spectroscopic diagnostics of the extended solar
corona structure and dynamics of solar wind
source regions

• MAIN RESULTS
• Determination of the main physical parameters
  inside several streamers and streamer-coronal
  hole interface regions observed with high
  radial and latitudinal resolution during
  different phases of the solar activity cycle.
  Detection of sharp variations across the streamer
  boundaries and peculiar kinetic and dynamical
  plasma responses, formally reminiscent of
  ion-cyclotron resonant dissipation of high
  frequency Alfven waves ( Spadaro, Ventura,
  Cimino, Romoli, AA, 2005 Ventura, Spadaro,
  Cimino, Romoli, AA, 2005) .
• Determination, for the first time, of the H I
  outflow velocities
  inside a streamer observed during the
  declining phase of the solar
  cycle
  (Spadaro, Susino,
  Ventura,Vourlidas, Landi, AA, 2007).

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• Ground-based EST (European Solar Telescope)
• 4 m. telescope - Participation in the
  Design Phase Activities
• 
  approved and financed by EU under FP 7
• 
  Kick-off February 2008

• Space HELEX Solar Orbiter Programme
• METIS (Multi-Experiment Telescopes for Imaging
  and Spectroscopy)
• Combined imaging and ultraviolet spectrometer
  instrument proposed
• for the scientific payload of Solar Orbiter
• Proposal submission deadline January 15, 2008

Thank you !