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Many studies assume that the solar irradiance in the EUV can be decomposed into different contributions, which makes the modelling of the spectral variability considerably easier. We consider a different approach, in which these contributions are not imposed a priori but are effectively and robustly inferred from spectral irradiance measurements. This is a source separation problem with a positivity constraint, for which we use a Bayesian solution. 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.
We benchmark new atomic data against a selection of irradiances obtained from medium-resolution quiet Sun spectra in the EUV, from 60 to 1040 AA. We use as a baseline the irradiances measured during solar minimum on 2008 April 14 by the prototype (PE
We used data from the Helioseismic and Magnetic Imager (HMI), and Atmospheric Imaging Assembly (AIA) on the textit{Solar Dynamics Observatory} (SDO) to study coronal loops at small scales, emerging in the quiet Sun. With HMI line-of-sight magnetogram
The present study reports the discovery of Sun-like stars, namely main-sequence stars with $T_{rm eff}$, $log g$ and rotation periods $P_{rot}$ similar to solar values, presenting evidence of surface differential rotation. An autocorrelation of the t
In a variant of communication complexity tasks, two or more separated parties cooperate to compute a function of their local data, using a limited amount of communication. It is known that communication of quantum systems and shared entanglement can
We illustrate properties of guided waves in terms of a superposition of body waves. In particular, we consider the Love and SH waves. Body-wave propagation at postcritical angles--required for a total reflection--results in the speed of the Love wave