Solar Dynamo Solar Cycle Spot Distribution Emerging Active Regions Solar Wind Transient Events Coronal Diagnostics and Modelling What’s next?
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
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
Structure and Evolution of the Butterfly Diagram Cycles 20, 21 & 22 • Maunder’s 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
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?
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)
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 Results
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
A B 17:35 U.T. (b) 18:10 U.T. (a) 18:40 U.T. (d) 19:09 U.T. (c) 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.
Solaire = Solar Atmospheric and interplanetary Research Solaire is AResearchTrainingNetworkapproved and financed by the European Commissionunder 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
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. A&A, 2007 • Chemical composition: photospheric, with • small variations from region to region • Lanzafame et al. A&A, 2005; Lang et al. A&A, 2007
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
Spectroscopic diagnostics of the extended solar corona: structure and dynamics solar wind source regions Determining the physical conditionsof 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.
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, A&A, 2005; Ventura, Spadaro, Cimino, Romoli, A&A, 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, A&A, 2007). Spectroscopic diagnostics of the extended solar corona: structure and dynamics of solar wind source regions
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 !