We summarize recent theoretical results dealing with the formation of massive stellar systems. The key premise is the high stellar density which leads to a very efficient star forming process in the so called positive feedback mode. Multiple implications arise from such models, e.g., much less mechanical energy exits the starburst process and much

In this work we study the physical properties of star-forming galaxies selected in an Hα near-infrared narrow-band survey tuned for redshift z=0.84 (Villar et al. 2008, 2011). Also, we present a sample at z˜1 with mass greater than 10^{10} M_{&sun;} with Hα emission. The observations were carried out with WHT/LIRIS (see Sánchez de Miguel et al

PHI, Polarimetric and Helioseismic Imager, is an instrument for solar observations that will go on board the Solar Orbiter mission (ESA/NASA), to be launched on 2017. This mission will orbit the Sun getting as close as 0.28 AU. It is also an out of the ecliptic mission which will provide a better, more direct observation of high solar latitudes. SO

Spectroscopic and spectropolarimetric observations with high spectral resolution provide extremely rich information on the physical conditions of distant celestial objects; sometimes, even the mere presence of a spectroscopic or polarimetric pattern may offer fundamental insights. But these are photon-starving techniques. Signals are often at the

Massive stars (M ≥ 9 M_{&sun;}) are usually formed in OB associations, consisting of one or more not very massive open clusters and a halo of scattered young stars. The study of these open clusters can provide clues about how stellar formation proceeds from the parent molecular clouds. We present first results on a project to understand sequential

The solar spectrophotometer "Mark-I", located at the Observatorio del Teide and continuously operated for the latest 36, provides a high precision measurement of the radial velocity of the Sun-as-a-star which has enabled the study of the small velocity fluctuations produced by normal modes solar oscillations and the characterization of its spectrum