The EUV Sun as the superposition of elementary Suns

Pierre-Olivier Amblard (1) , Saïd Moussaoui (2) , Thierry Dudok de Wit (3) , Jean Aboudarham (4) , Matthieu Kretzschmar (3) , Jean Lilensten (5) , Frédéric Auchère (6)

1 GIPSA-SIGMAPHY - GIPSA - Signal Images Physique
2 IRCCyN - Institut de Recherche en Communications et en Cybernétique de Nantes
3 LPCE - Laboratoire de physique et chimie de l'environnement
4 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
5 LPG - Laboratoire de Planétologie de Grenoble
6 IAS - Institut d'astrophysique spatiale

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.

Domaines: Traitement du signal et de l'image [eess.SP]; Traitement du signal et de l'image [eess.SP]

Pierre-Olivier Amblard, Saïd Moussaoui, Thierry Dudok de Wit, Jean Aboudarham, Matthieu Kretzschmar, et al.. The EUV Sun as the superposition of elementary Suns. Astronomy and Astrophysics - A&A, 2008, 487, pp.L13-L16. ⟨10.1051/0004-6361:200809588⟩. ⟨hal-00325235⟩