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The EUV Sun as the superposition of elementary Suns

TitreThe EUV Sun as the superposition of elementary Suns
Type de publicationJournal Article
Year of Publication2008
AuteursAmblard, PO, Moussaoui, S, de Wit, TD, Aboudarham, J, Kretzschmar, M, Lilensten, J, Auchere, F
JournalAstronomy & Astrophysics
Date PublishedAug
ISBN Number0004-6361
Numéro d'accèsWOS:000258327900001

Aims. Many studies assume that the solar irradiance in the EUV can be decomposed into different contributions, which makes modelling the spectral variability considerably easier. We consider a different approach in which these contributions are not imposed a priori but effectively and robustly inferred from spectral irradiance measurements. Methods. This is a source separation problem with a positivity constraint, for which we use a Bayesian solution. Results. Using five years of daily EUV spectra recorded by the TIMED/SEE satellite, we show that the spectral irradiance can be decomposed into three elementary spectra. Our results suggest that they describe different layers of the solar atmosphere rather than specific regions. The temporal variability of these spectra is discussed.

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