Horizontal flow fields in and around a small active region The transition period between flux emergence and decay

0488883 - ASÚ 2018 RIV FR eng J - Journal Article
Verma, M. - Denker, C. - Balthasar, H. - Kuckein, C. - Gonzalez Manrique, S. J. - Sobotka, Michal - Gonzalez, N.B. - Hoch, S. - Diercke, A. - Kummerow, P. - Berkefeld, T. - Collados Vera, M. - Feller, A. - Hofmann, A. - Kneer, F. - Lagg, A. - Löhner-Böttcher, J. - Nicklas, H. - Pastor Yabar, A. - Schlichenmaier, R. - Schmidt, D. - Schmidt, W. - Schubert, M. - Sigwarth, M. - Solanki, S.K. - Soltau, D. - Staude, J. - Strassmeier, K.G. - Volkmer, R. - von der Lühe, O. - Waldmann, T.A.
Horizontal flow fields in and around a small active region The transition period between flux emergence and decay.
Astronomy & Astrophysics. Roč. 596, December (2016), A3/1-A3/12. ISSN 0004-6361. E-ISSN 1432-0746
R&D Projects: GA MŠMT(CZ) 7E13003
Keywords : Sun * photosphere * magnetic fields
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 5.014, year: 2016

Combining high-resolution and synoptic observations aims to provide a comprehensive description of flux emergence at photospheric level and of the growth process that eventually leads to a mature active region. The computed growth rates for photometric area, magnetic area, and magnetic flux are about twice as high as the respective decay rates. The space-time diagram using HMI magnetograms of five days provides a comprehensive view of growth and decay. It traces a leaf-like structure, which is determined by the initial separation of the two polarities, a rapid expansion phase, a time when the spread stalls, and a period when the region slowly shrinks again. The separation rate of 0.26 km s(-1) is highest in the initial stage, and it decreases when the separation comes to a halt. Horizontal plasma velocities computed at four evolutionary stages indicate a changing pattern of inflows. In LCT maps we find persistent flow patterns such as outward motions in the outer part of the two major pores, a diverging feature near the trailing pore marking the site of upwelling plasma and flux emergence, and low velocities in the interior of dark pores. We detected many elongated rapidly expanding granules between the two major polarities, with dimensions twice as large as the normal granules.

Permanent Link: http://hdl.handle.net/11104/0283402