We have reproduced some sunspot wave signatures obtained from spectropolarimetric observations through 3D MHD numericalsimulations. The results of the simulations arecompared with the oscillations observed simultaneously at different heights from the SiI lambda10827Å line, HeI lambda10830Å line, the CaII H core and the FeI blends at the wings of

We present a summary of results obtained by Poidevin & Bastien (2006) in the GF-9 core region. Multi-scale analysis is used and suggests that an original poloidal magnetic field could have been twisted by a rotating elongated (core+envelope) structure.

L-type ultra-cool dwarfs are known to have a dusty atmosphere. Surface heterogeneities, due to cloud patterns or rotationally-induced oblateness, would result in an imperfect polarization cancellation and a small, but non-zero net polarization. The measurement of linear polarization could shed light on the dust distribution and oblateness of those

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Context. Properties of galaxies depend on their large-scale environment. As the influence of active galactic nuclei (AGN) in galaxy evolution is becoming more evident, their large-scale environments may help us understand the evolutionary processes leading to activity. The effect of activity can be seen particularly by showing whether different

The luminosity function is not only crucial to know the stellar density distribution in space, and thus to know the structure of the Galaxy; it also allows the determination of the stellar mass function using the mass-luminosity relationship. The luminosity and mass functions are crucial to understand star formation and the evolution of the Milky