Astron. Astrophys. 359, 373-380 (2000)

Spatial and temporal relations between magnetic elements and bright points in the photospheric network

R. Muller ¹, A. Dollfus ³, M. Montagne ², J. Moity ³ and J. Vigneau <sup>2

1</sup> Observatoire du Pic du Midi, BP 136, 65201 Bagnéres de Bigorre, France
² Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France
³ Observatoire de Meudon, DASOP, 92195 Meudon Cedex, France

Received 3 June 1998 / Accepted 20 January 2000

Abstract

28 min time series of high resolution magnetograms, continuum filtergrams and line core filtergrams have been obtained in the line FeI 6173, with the 50 cm refractor of the Pic du Midi Observatory, in a quiet area near the solar disk center. Their comparison shows that every bright point of the photospheric network coincides better than 0"5 with a magnetic element of small size (smaller than 1"). The maximum of magnetic field strength of a magnetic element does not necessarily occur at the same time as the maximum of brightness. Such spatial and temporal relations cannot be explained by static models of flux tubes, but they can be by a dynamic flux tube model, as computed by Steiner et al. (1996). The observations also show that a magnetic element present in the network becomes bright and forms a bright point when it is compressed by the surrounding granules as they converge. This is an indication that the dynamics of granulation plays a major role in the concentration of the magnetic field into thin flux tubes, near the surface of the Sun.

Key words: Sun: granulation Sun: magnetic fields Sun: photosphere

This article contains no SIMBAD objects.

Contents

• 1. Introduction
• 2. Observations
• 3. Image processing and creation of magnetograms
  • 3.1. Digitization
  • 3.2. Frames alignment and image destretching
  • 3.3. Creation of magnetograms
  • 3.4. Line and core continuum filtergrams
• 4. Description of filtergrams and magnetograms
  • 4.1. Continuum filtergrams
  • 4.2. Line core filtergrams
  • 4.3. Longitudinal field magnetograms
• 5. Results and discussion: spatial and temporal relations between magnetic elements and network bright points
• 6. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: June 30, 2000
helpdesk.link@springer.de