paper

Velocities measured in small scale solar magnetic elements

arXiv:astro-ph/0611741 · doi:10.1086/509754

Abstract

We have obtained high resolution spectrograms of small scale magnetic structures with the Swedish 1-m Solar Telescope. We present Doppler measurements at $0\farcs{2}$ spatial resolution of bright points, ribbons and flowers and their immediate surroundings, in the C {\small{I}} 5380.3 Å line (formed in the deep photosphere) and the two Fe {\small{I}} lines at 5379.6 Å and 5386.3 Å. The velocity inside the flowers and ribbons are measured to be almost zero, while we observe downflows at the edges. These downflows are increasing with decreasing height. We also analyze realistic magneto-convective simulations to obtain a better understanding of the interpretation of the observed signal. We calculate how the Doppler signal depends on the velocity field in various structures. Both the smearing effect of the non-negligible width of this velocity response function along the line of sight and of the smearing from the telescope and atmospheric point spread function are discussed. These studies lead us to the conclusion that the velocity inside the magnetic elements are really upflow of the order 1--2 km s while the downflows at the edges really are much stronger than observed, of the order 1.5--3.3 km s.

10 pages,9 figures, accepted in ApJ

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