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Astron. Astrophys. 356, 301-307 (2000)

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Consistent determination of quasi force-free magnetic fields from observations in solar active regions

R. Berton

Observatoire de Paris, DASOP, 92195 Meudon Principal Cedex, France

Received 11 January 1999 / Accepted 10 November 1999


The classical concept of extrapolating the photospheric magnetic field from line-of-sight measurements [FORMULA] assuming a pure force-free field is revisited and a new procedure is proposed which is based on:

  1. non-vanishing magnetic forces,

  2. known horizontal forces from direct measurement of pressure or a related quantity (continuum brightness),

  3. a small perturbation to the potential or linear force-free field which matches the [FORMULA] distribution.

Orders of magnitude are estimated from observational data and they show that magnetic forces should be actually as large as expected from dimensional analysis.

Key words: Sun: activity – Sun: magnetic fields

This article contains no SIMBAD objects.


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© European Southern Observatory (ESO) 2000

Online publication: March 28, 2000