The EUV Sun as the superposition of elementary Suns

International audienceAims. 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

The Heliophysics Feature Catalogue, a tool for the study of solar features

The behavior of filaments and prominences during the Solar Cycle is a signature of Sun's activity. It is therefore important to follow their evolution during the cycle, in order to be able to associate it with the various phases of the Solar Cycle as well as with other Solar features or events. The virtual observatory HELIO provides information that can be used for such studies, especially its Heliophysics Feature Catalogue gives a unique access to the description of various features during around one cycle. Features available are: filaments, prominences, photospheric and coronal active regions, coronal radio emission, type III radio bursts, coronal holes and sunspots. Web interfaces allow the user to query data for these features. Useful information can also be shared with other HELIO services, such as Heliophysics Event Catalogue, which provides access to dozens of tables of events such as flares, CME

Le soleil comme superposition de soleils élémentaires

Le but de ce travail est la décomposition de l'activité solaire en des activités élémentaires interprétables physiquement. Nous utilisons les mesures du spectre solaire issues de l'instrument SEE embarqué par le satellite TIMED. Les mesures journalières du spectre VUV obtenues sur cinq années autorisent l'utilisation d'un algorithme MCMC de séparation bayésienne de sources positives. Nous montrons que le spectre solaire peut être décomposé en la somme pondérée de trois spectres élémentaires, deux étant clairement représentatifs de zones différentes du soleil, le dernier étant plus difficilement interprétable

Data collection and mining in Solar Physics

International audienc

Guide stellaire

National audienc

Statistical study of solar filaments since 1919

International audienc

Etude du transfert et du depot de l'energie dans les eruptions solaires

SIGLECNRS T 59819 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Atlas du ciel et des étoiles

National audienc

Cartographie céleste

National audienc

Statistical study of solar filaments since 1919

International audienc