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Analyse des variations de l'enveloppe chromosphérique du Soleil et son Ovalisation

Abstract : We review the actual problem of solar physics and space weather to show how important it is to understand the behaviour and the origin of the coronal magnetic field which emerges through the chromosphere. It is shown that 1D hydrostatic models are insufficient to describe the extended chromosphere above the 2Mm heights and empirical models are in state of infancy. All the past methods to measure the thickness and the shape of the chromosphere are critically analysed, especially methods using full disk imaging in chromospheric lines. The main sources of distorsion due to instruments and the Earth atmosphere are studied and pratical computed values of the differential refraction effect are given, as well as the needed parameters for making solar off limb observations. Precise measurements of the variations of the thickness of the extended chromosphere are analysed using the available observations (outside of active regions), including some original but limited data obtained with the best coronagraph of NSO – Sacramento Peak Observatory in New-Mexico, USA. New values of chromospheric thicknesses are reported using a relative method for both the minimum and especially the maximum sunspot activity, showing that the chromospheric prolateness is changing and is of magnetic origin. To collect more systematic data in the future, an efficient instrumentation to be developped at the Luanda University Solar Laboratory is described and some preliminary results using a prototype are given.
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Contributor : Jaime Vilinga <>
Submitted on : Wednesday, January 20, 2010 - 2:05:51 PM
Last modification on : Wednesday, December 9, 2020 - 3:16:54 PM
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  • HAL Id : tel-00448903, version 1

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Jaime Vilinga. Analyse des variations de l'enveloppe chromosphérique du Soleil et son Ovalisation. Astrophysique [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2006. Français. ⟨tel-00448903⟩

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