EDP Sciences
Free access
Volume 437, Number 3, July III 2005
Page(s) 1069 - 1080
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20042593

A&A 437, 1069-1080 (2005)
DOI: 10.1051/0004-6361:20042593

The wings of Ca II H and K as solar fluxtube diagnostics

V. A. Sheminova1, R. J. Rutten2, 3 and L. H. M. Rouppe van der Voort3, 4

1  Main Astronomical Observatory, National Academy of Sciences of the Ukraine, 27 Akademika Zabolotnoho St., 03680 Kiev, Ukraine
    e-mail: shem@mao.kiev.ua
2  Sterrekundig Instituut, Utrecht University, Postbus 80 000, 3508 TA Utrecht, The Netherlands
3  Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway
4  Center of Mathematics for Applications, University of Oslo, PO Box 1053 Blindern, 0316 Oslo, Norway

(Received 22 December 2004 / Accepted 15 March 2005 )

We combine high-resolution Ca II H and K spectrograms from the Swedish Vacuum Solar Telescope with standard fluxtube modeling to derive photospheric temperature and velocity stratifications within individual magnetic elements in plage near a sunspot. We find that 1D on-axis modeling gives better consistency than spatial averaging over flaring-fluxtube geometry. Our best-fit temperature stratifications suggest that magnetic elements are close to radiative equilibrium throughout their photospheres. Their brightness excess throughout the H and K wings compared with the quiet photosphere is primarily due to low density, not to mechanical heating. We conclude that the extended H and K wings provide excellent fine-structure diagnostics for both high-resolution observations and simulations of the solar photosphere.

Key words: Sun: photosphere -- Sun: magnetic fields -- Sun: faculae, plages

© ESO 2005