Context: The peculiar three-peak structure of the linear polarization profile shown in the second solar spectrum by the Ba ii line at 4554 Å has been interpreted as the result of the different contributions coming from the barium isotopes with and without hyperfine structure. In the same spectrum, a triple peak polarization signal is also observed

The existence of compact H ii regions around massive stellar clusters with ages exceeding several Myr challenges our understanding of the physical processes occurring inside such clusters, and their impact on the interstellar medium of the host galaxy. Here, we summarize our recent results dealing with the hydrodynamics of matter ejected by massive

Context: The topology of penumbral magnetic fields is poorly known. The satellite Hinode has recently revealed penumbral structures of a magnetic polarity that is opposite to the main sunspot polarity. They may be direct confirmation that magnetic field lines and mass flows return to the solar interior throughout the penumbra, a configuration

In this contribution we examine the problem of inferring ages and initial cluster masses from synthesis models at the limit of low-mass clusters ( M≤ a few ×104 M⊙). We show that it is not possible to apply directly synthesis models using standard methods to such clusters, since the basic hypothesis implicit in the models (a fixed proportionality

We show how inferences of the solar internal rotation rate depend on different aspects of the mode fitting procedure. We study the stability of the rotation rate and its variation with time through inversions of frequency splittings data sets computed from fitting 364, 728 and 2088-day long Michelson Doppler Imager (MDI) time series, 72-day long