2009/12/10 by D. Utz, A. Hanslmeier, R. Muller +3 · 2 citations
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Amplitude #Coronal loop #Deconvolution #Distribution function #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Magnetic field #Photosphere #Range (aeronautics) #Rayleigh distribution #Smoothing #Solar and Space Plasma Dynamics #Solar physics #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/200913085
Astronomy and Astrophysics (in press)
arxiv created 2009/12/10 · openalex publication_date 2009/12/11 · arxiv updated 2015/05/14 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
<i>Context. <i/>Small-scale magnetic fields in the solar photosphere can be identified in high-resolution magnetograms or in the G-band as magnetic bright points (MBPs). Rapid motions of these fields can cause magneto-hydrodynamical waves and can also lead to nanoflares by magnetic field braiding and twisting. The MBP velocity distribution is a crucial parameter for estimating the amplitudes of those waves and the amount of energy they can contribute to coronal heating.<i>Aims. <i/>The velocity and lifetime distributions of MBPs are derived from solar G-band images of a quiet sun region acquired by the Hinode/SOT instrument with different temporal and spatial sampling rates.<i>Methods. <i/>We developed an automatic segmentation, identification and tracking algorithm to analyse G-Band image sequences to obtain the lifetime and velocity distributions of MBPs. The influence of temporal/spatial sampling rates on these distributions is studied and used to correct the obtained lifetimes and velocity distributions for these digitalisation effects.<i>Results. <i/>After the correction of algorithm effects, we obtained a mean MBP lifetime of min and mean MBP velocities, depending on smoothing processes, in the range of (1–2) . Corrected for temporal sampling effects, we obtained for the effective velocity distribution a Rayleigh function with a coefficient of . The <i>x<i/>- and <i>y<i/>-components of the velocity distributions are Gaussians. The lifetime distribution can be fitted by an exponential function.