Motivation

The filamentary structure is a fundamental property of solar magnetic fields. Recent high-resolution observations and radiative MHD numerical simulations revealed close links between the filamentary structures and plasma dynamics in sunspots and magnetic network. A new emerging paradigm is that the mechanisms of the filamentary structuring and large-scale organization are natural consequences of turbulent magnetoconvection on the Sun. Numerical simulations have provided new explanations to the filamentary structure of sunspots, the Evershed effect and the moving magnetic features. However, many problems remain unsolved because of difficulties with analysis and interpretation of spectro-polarimetric observations and with modeling of the turbulent magnetohydrodynamics processes.

Our main goals are to discuss the recent advances, uncertainties and unsolved problems, compare the models and observations, and develop new approaches to simulations and data analysis of the filamentary magnetic structure and dynamics of the Sun from ground-based telescopes and the space missions Hinode and Solar Dynamics Observatory.

Scientific objectives

• What are the structure and dynamics of the filamentary magnetic structures and ubiquitous horizontal fields in the quiet-Sun regions?
• What are the evidences of the unresolved "hidden" magnetism?
• What are the roles of emerging magnetic flux and local dynamo in the formation of the photospheric and chromospheric networks?
• What physical conditions are required for the formation of large-scale structures and sunspots?
• What are the inferences on the formation of magnetic structures from surface observations and local helioseismology?
• What are the mechanisms of the filamentary structure and dynamics of sunspot umbra and penumbra?
• What is the role of the filamentary structuring in large-scale solar magnetism?
• What future observations and simulations are needed to advance our understanding of the filamentary structure of solar magnetic fields?

List of team members

• M. Bianda, Istituto Ricerche Solari Locarno, Switzerland
• S. Criscuoli, Osservatorio Astronomico di Roma, Italy
• I. Kitiashvili, Stanford University, USA
• E. Khomenko, Instituto de Astrofísica de Canarias, Spain
• L. Kleint, Institute of Astronomy, ETH Zurich, Switzerland
• A. Kosovichev, Stanford University, USA
• M. Kubo, National Astronomical Observatory, Japan
• R. Rezaei, Kiepenheuer-Institut für Sonnenphysik, Germany
• A. Sainz Dalda, Stanford-Lockheed Institute for Space Research, USA
• R. Schlichenmaier, Kiepenheuer-Institut für Sonnenphysik, Germany
• O. Steiner, Kiepenheuer-Institut für Sonnenphysik, Germany
• J. Stenflo, Institute of Astronomy, ETH Zurich, Switzerland
• R. Wenzel, Institute of Astronomy, ETH Zurich, Switzerland
• V. Yurchyshyn, Big Bear Solar Observatory of New Jersey Institute of Technology, USA

Schedule of the project

• Meeting I: 15-19 November 2010, ISSI, Bern
• Meeting II: 21-25 November 2011, ISSI, Bern

2012

Bello Gonzalez N., Kneer F., Schlichenmaier R.
Shear and vortex motions in a forming sunspot. Twist relaxation in magnetic flux ropes.
Astronomy & Astrophysics, 538, A62-A66, 2012.

Kleint L.
Spectropolarimetry of C-class flare footpoints.
Astrophysical Journal, 748, 138-149, 2012.

Kitiashvili I.N., Kosovichev A.G., Mansour N.N., Lele S.K., Wray A.A.
Vortex tubes of turbulent solar convection.
Physica Scripta, 86, 018403, 2012.

Rezaei R., Bello Gonzalez N., Schlichenmaier R.
The formation of sunspot penumbra. I. Magnetic field properties.
Astronomy & Astrophysics, 537, A19-A32, 2012.

Rezaei R., Beck, C., Schmidt, W.
Variation in sunspot properties between 1999 and 2011 as observed with the Tenerife Infrared Polarimeter.
Astronomy & Astrophysics, 541, A60-A68, 2012.

Sainz Dalda A., Vargas Dominguez S., Tarbell T.D.
Magnetic topology of a naked sunspot: is it really naked?
Astrophysical Journal Letters, 746, L13-L17, 2012.

Sainz Dalda A., Martínez-Sykora J., Bellot Rubio L, Title A.
Study of single-lobed circular polarization profiles in the quiet Sun.
Astrophysical Journal, 748, 38-61, 2012.

Stenflo J.O.
Scaling laws for magnetic fields on the quiet Sun.
Astronomy & Astrophysics, 541, A17-A28, 2012.

Stenflo J.O., Kosovichev, A.G.
Bipolar magnetic regions on the Sun: global analysis of the SOHO/MDI data set.
Astrophysical Journal, 745, 129-140, 2012.

Coming soon...

Kitiashvili I.N. Abramenko V.I., Goode P.R., Kosovichev A.G., Lele S.K., Mansour N.N., Wray A.A., Yurchyshyn V.B.
Turbulent Kinetic Energy Spectra of Solar Convection from NST Observations and Realistic MHD Simulations.
ArXiv:1206.5300

Steiner O., Rezaei R.
Recent advances in the exploration of the small-scale structure of the quiet solar atmosphere: vortex flows, the horizontal magnetic field, and the Stokes-V line-ratio method.
ArXiv:1202.4040

2011

Criscuoli S., Ermolli I., Fontenla J., Giorgi F., Rast M., Solanki S. K., Uitenbroek H.
Radiative emission of solar features in Ca II K.
Memorie della Societa Astronomica Italiana, 81, 773-776, 2010.

Ermolli I., Criscuoli S., Uitenbroek H., Giorgi F., Rast M. P., Solanki S. K.
Radiative emission of solar features in the Ca II K line: comparison of measurements and models.
Astronomy & Astrophysics, 523, A55-A64, 2010.

Ilonidis S., Zhao J., Kosovichev A.
Detection of Emerging Sunspot Regions in the Solar Interior.
Science, 333 (6045), 993-996, 2011.

Kitiashvili I.N., Kosovichev A.G., Mansour N.N. Wray A.A.
Excitation of acoustic waves by vortices in the quiet Sun.
Astrophysical Journal Letters, 727, L50-L54, 2011.

Kitiashvili I.N., Kosovichev A.G., Mansour N.N. Wray A.A.
Numerical MHD simulations of solar magnetoconvection and oscillations in inclined magnetic field regions.
Solar Physics, 268, 2, 283-291, 2011.

Kitiashvili I.N., Kosovichev A.G., Wray A.A., Mansour N.N.
Realistic MHD simulations of magnetic self-organization in solar plasma.
Proc. of IAU Symposium 274 "Advances in Plasma Astrophysics", 6, 120-124, 2011.

Kitiashvili I.N., Kosovichev A.G., Wray A.A., Mansour N.N.
Numerical simulations of magnetic structures.
Proc. of IAU Symposium 273 "The Physics of Sun and Star Spots", 6, 315-319, 2011.

Kosovichev A.G.
Advances in global and local helioseismology: an introductory review.
In "Pulsation of the Sun and Stars", Lecture Notes in Physics, Vol. 832, Rozelot, Jean-Pierre; Neiner, Coralie (Eds.), 3-84, 2011.

Kosovichev A.G.
Investigations of solar plasma in the interior and corona from Solar Dynamics Observatory.
Proc. of IAU Symposium 274 "Advances in Plasma Astrophysics", 6, 287-290, 2011.

Schlichenmaier R., Bello Gonzalez N., Rezaei R.
The formation of a penumbra as observed with the German VTT and SoHO/MDI.
Proc. of IAU Symposium 273 "The Physics of Sun and Star Spots", 6, 134-140, 2011.

Stenflo, J. O.
Collapsed, uncollapsed, and hidden magnetic flux on the quiet Sun.
Astronomy & Astrophysics, 529, A42-A65.

Yurchyshyn V.B., Goode P.R., Abramenko V.I., Steiner O.
On the origin of intergranular jets.
Astrophysical Journal Letters, 736, L35-L40, 2011.

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Contact:
Irina Kitiashvili (irinasun_at_stanford_dot_edu)
Jennifer Zaugg (jennifer.zaugg_at_issibern_dot_ch)
Secretary of International Space Science Institute,
Tel.: +41-31-631 48 96 Fax: +41-31-631 48 97

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