Volume 577, May 2015
|Number of page(s)||8|
|Published online||13 May 2015|
Estimating the magnetic field strength from magnetograms
1 Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
2 Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
Received: 21 March 2014
Accepted: 25 March 2015
A properly calibrated longitudinal magnetograph is an instrument that measures circular polarization and gives an estimation of the magnetic flux density in each observed resolution element. This usually constitutes a lower bound of the field strength in the resolution element, given that it can be made arbitrarily large as long as it occupies a proportionally smaller area of the resolution element and/or becomes more transversal to the observer while still produce the same magnetic signal. However, we know that arbitrarily stronger fields are less likely – hG fields are more probable than kG fields, with fields above several kG virtually absent – and we may even have partial information about their angular distribution. Based on a set of sensible considerations, we derive simple formulae based on a Bayesian analysis to give an improved estimation of the magnetic field strength for magnetographs.
Key words: Sun: magnetic fields / methods: data analysis / methods: statistical
© ESO, 2015
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