2006/11/23 by Øystein Langangen, Oystein Langangen, Mats Carlsson +2 · 4 citations
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Doppler effect #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Line (geometry) #Line-of-sight #Magnetic field #Resolution (logic) #Solar and Space Plasma Dynamics #Solar telescope #Spectral line #Telescope #astro-ph
paper · pdf · doi:10.1086/509754
published as Astrophys.J.655:615-623,2007 · 10 pages,9 figures, accepted in ApJ
arxiv created 2006/11/23 · openalex publication_date 2007/01/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We have obtained high-resolution spectrograms of small-scale magnetic structures with the Swedish 1-m Solar Telescope. We present Doppler measurements at 0.2'' spatial resolution of bright points, ribbons, and flowers, and their immediate surroundings, in the C I λ5380.3 line (formed in the deep photosphere) and the two Fe I lines at 5379.6 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 magnetoconvective 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 nonnegligible 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 is really upflow of order 1-2 km s -1 , while the downflows at the edges really are much stronger than observed, of order 1.5-3.3 km s -1 .