Issue |
A&A
Volume 487, Number 2, August IV 2008
|
|
---|---|---|
Page(s) | L13 - L16 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:200809588 | |
Published online | 01 July 2008 |
Letter to the Editor
The EUV Sun as the superposition of elementary Suns
1
GIPSA-lab, DIS (UMR CNRS 5216, INP Grenoble), BP 46, 38402 Saint-Martin d'Hères, France e-mail: bidou.amblard@gipsa-lab.inpg.fr
2
IRCCYN (UMR CNRS 6597, ECNantes), 1 rue de la Noé, BP 92101, 44321 Nantes Cedex 3, France
3
LPCE (UMR 6115 CNRS-Université d'Orléans), 3A avenue de la Recherche Scientifique, 45071 Orléans, France
4
LESIA (UMR CNRS 8109, Observatoire de Paris), 5 place Jules Janssen, 92195 Meudon, France
5
LPG (UMR 5109 CNRS-Université Joseph Fourier), Bâtiment de Physique D, BP 53, 38041 Saint-Martin d'Hères Cedex, France
6
IAS (UMR 8617 CNRS-Université Paris-Sud), 91045 Orsay, France
Received:
15
February
2008
Accepted:
27
May
2008
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.
Key words: Sun: activity / Sun: UV radiation / methods: data analysis / methods: statistical
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.