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conference "Solar and Stellar Dynamos and Cycles"
chaired by Alexander Kosovichev (Stanford University) , Maarit Korpi (Observatory, Helsinki University)
  from Saturday 26 September 2009 (09:00)
to Monday 26 October 2009 (18:00)
at Nordita
  Description:

Nordita Events is where most of the daily talks of the program are being annouced.

Time table for the Ilkka fest link.

Programme routine and workshop

The first two weeks of the programme are dedicated to stellar dynamo theory and observations, and the last two for solar magnetic activity, dynamos and data assimilation methods. We plan to have informal gatherings over coffee every day at 10:00 and 16:00. For some of the days we shall schedule talks or formal discussions at 10:30.

We are also organising a special workshop during the 5th-6th of October in the honor of the 70th birthday of Professor Ilkka Tuominen. We aim to cover topics that Ilkka has actively pursued during his long and successful scientific career, namely spectroscopy and Doppler imaging of stellar magnetic activity, stellar activity cycles and the flip-flop phenomenon, and stellar dynamo theory. If you plan to attend all or part of the program, or if you would like to come to the special workshop on 5-6 October, please register on the page indicated above. Please indicated if you would like to give a talk. Alternatively, you may just email any of us. The most up-to-date time table with preliminary allocation of chair persons is on this link.

Background

Understanding the origin of solar and stellar magnetic fields is one of the central problems of physics and astrophysics, and a key to understanding the cosmic magnetism, in general. There are two main difficulties in studying this problem: 1) magnetic fields are generated by turbulent dynamos in convection zones below the visible surface, not accessible by direct observations; 2) solar and stellar magnetic activity is a multi-scale phenomenon, involving physical processes on very small scales, probably, below the current observational limit, and at the same time showing remarkable large-scale spatial and temporal organizations over a whole star. The prime target of our investigation is the Sun, which serves as the Rosetta Stone in this field and holds the key to unlocking the secrets of magnetic field generation in the Universe. The most detailed observational data and theoretical models have been obtained for the Sun, but a very significant progress has also been achieved in observations and theories of magnetism on other stars.

Observationally, most efforts for solving the problem of solar and stellar magnetism are focused on developing helio- and asteroseismology for probing the structure and dynamics inside the Sun and stars and detecting changes associated with magnetic fields, on high- resolution observations for probing small-scale and even unresolved magnetic structures and their organization and evolution, and on studying large-scale patterns of sunspots and starspots and magnetic activity cycles.

Theoretically, this problem is addressed by developing physical models at three different levels of the spatial and temporal domain: 1) direct 3D MHD simulations of small volumes of the convection zone with the highest possible resolution to understand properties of MHD turbulence, helicity, diffusion and saturation mechanisms; 2) 3D mean-field and full MHD simulations of the interior of the Sun and stars for the global dynamo on the scale of the activity cycles; 3) non-linear dynamical models to investigate long-term evolution of the dynamo. These approaches have been developed independently and quite successfully by different groups.

Data assimilation is a powerful analysis method in which observed information is accumulated into dynamical models taking into account physical constraints and properties. This approach makes possible efficient and accurate estimations of physical properties which cannot be observed directly, and obtain better understanding of the underlying physics and develop forecast models.

At the beginning and the end of this program, we plan to hold short (2-3 days) general discussion meetings. Also, during the program, we will hold topical discussion sessions, as these are needed. Most work will be done in focused working groups. In particular, we propose the following initial tasks for discussion and investigation:

  • Physics of MHD turbulence and turbulent dynamo
  • Numerical dynamo simulations
  • Observational constraints on the solar and stellar dynamos
  • Mathematics of prediction and data assimilation

    Program details

  • Material:
    files pictures 
     

    Monday 28 September 2009 toptop
    10:00 
    Welcome coffee

    10:30->12:00    Planning session
    12:00 
    Lunch

    Tuesday 29 September 2009 toptop
    10:00 
    Morning coffee and discussion

    Wednesday 30 September 2009 toptop
    10:00 
    Morning coffee and discussion

    10:30->12:30    Theoretical aspects of solar and stellar differential rotation

    Thursday 01 October 2009 toptop
    10:00 
    Morning coffee and discussion

    Friday 02 October 2009 toptop
    10:00 
    Morning coffee and discussion

    15:00->17:00    Solar dynamo and magnetic helicity
    15:00  Fine structure of solar butterfly diagrams for sunspots (20') Dmity Sokoloff

    Monday 05 October 2009 toptop

    09:00->10:30    Morning session 1 (Convener: Maarit Korpi (Univ. of Helsinki) )
    09:00  Opening remarks & Sunspot activity -- a shallow phenomenon? (30') Axel Brandenburg (Nordita)
    09:30  Some notes on sunspot statistics (30') Ilkka Tuominen (Observatory, Univ. of Helsinki)
    10:00  Stars through a Magnifying Glass: Doppler Imaging (30') Nikolai Piskunov (Univ. of Uppsala)
    10:30 
    Coffee

    11:00->12:30    Morning session 2 (Convener: Simon Candelaresi (NORDITA) )
    11:00  Doppler imaging of stellar magnetic fields: techniques and recent results (30') Oleg Kochukhov (Univ. of Uppsala)
    11:30  Kinematics and statistics on the sphere - about spots and 'flip-flop' (30') Jaan Pelt (Tartu Observatory)
    12:00  Extending the solar butterfly diagram into the past (30') Rainer Arlt (AIP)
    12:30 
    Lunch

    14:00->15:30    Afternoon session 1 (Convener: Kyösti Ryynänen (NORDITA) )
    14:00  Structure and stability of the magnetic solar tachocline (30') Guenther Ruediger (AIP)
    14:30  Detecting differential rotation from spectrometric and photometric observations (30') Thomas Hackman (Observatory, Univ. of Helsinki)
    15:00  The spectropolarimeters Sofin/Pepsi and the latest observational results (30') Ilya Ilyin (AIP)
    15:30 
    Coffee

    16:00->17:30    Afternoon session 2 (Convener: Koen Kemel (Nordita) )
    16:00  Helical properties of solar magnetic fields as a proxy of dynamo mechanism: results of 20 years monitoring (30') Kirill Kuzanyan (IZMIRAN)
    16:30  Formation of magnetic patches by turbulent effects of hydromagnetic stresses (30') Igor Rogachevskii (Ben Gurion University)
    17:00  Discussion (30')

    Tuesday 06 October 2009 toptop

    09:30->12:00    Morning session 1 (Convener: Fabio Del Sordo (NORDITA) )
    09:30  Non-linear Dynamical Modeling and Prediction of Solar Cycles (30') Irina Kitiashvili
    10:00  Emerging magnetic flux and Joy's Law (30') Alexander Kosovichev (Stanford University)
    10:30 
    Coffee

    11:00->12:30    Morning session 2 (Convener: Jörn Warnecke (NORDITA) )
    11:00  Convection driven dynamos in spherical wedge geometry (30') Petri Käpylä (University of Helsinki)
    11:30  Helicity of solar active regions from a dynamo (30') Piyali Chatterjee
    12:00  Curvature-stretching anticorrelation in Solar dynamos (30') Luiz Garcia de Andrade (Dept of theoretical physics, IF, UERJ)
    12:30 
    Lunch

    14:00->15:00    Afternoon session 1 (Convener: Gustavo Guerrero (NORDITA) )
    14:00  Mean-field dynamo models of rapidly rotating stars & Closing remarks (30') Maarit Korpi (Observatory, Helsinki University)
    14:30  Discussion (30')

    15:15->16:15    AlbaNova & Nordita colloqium: The Nobel Price in Physics 2009
    15:15  AlbaNova & Nordita colloqium: The Nobel Price in Physics 2009 (1h00')

    Wednesday 07 October 2009 toptop
    10:00 
    Morning coffee and discussion

    15:00->17:00    Pencil Code Tutorial

    Thursday 08 October 2009 toptop
    10:00 
    Morning coffee and discussion

    14:00->16:00    Instabilities (Tayler, MRI ...)

    Friday 09 October 2009 toptop
    10:00 
    Morning coffee and discussion

    10:30->12:30    Current issues in convection

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