We have selected the Galactic HII region M43, a close-by apparently spherical nebula ionized by a single star (HD37061, B0.5V) to investigate several topics of recent interest in the field of HII regions and massive stars. We perform a combined, comprehensive study of the nebula and its ionizing star by using as many observational constraints as possible. For this study we collected a set of high-quality observations, including the optical spectrum of HD3706, along with nebular optical imaging and long-slit spatially resolved spectroscopy. On the one hand, we have carried out a quantitative

Delta Scuti (δ Sct) stars are opacity-driven pulsators with masses of 1.5-2.5M⊙, their pulsations resulting from the varying ionization of helium. In less massive stars such as the Sun, convection transports mass and energy through the outer 30 per cent of the star and excites a rich spectrum of resonant acoustic modes. Based on the solar example, withno firm theoretical basis, models predict that the convective envelope in δ Sct stars extends only about 1 per cent of the radius, but with sufficient energy to excite solar-like oscillations. This was not observed before the Kepler mission, so

Las binarias de rayos X son sistemas formados por un objeto compacto (estrella de neutrones o agujero negro) y una estrella de tipo “normal”. El objeto compacto arranca materia de la estrella que orbita alrededor del objeto compacto formando un disco de acreción. Las binarias de rayos X transitorias son un tipo de binarias de rayos X que se caracterizan por estar la mayor parte de su vida en quietud. Ocasionalmente, el sistema entra en erupción, fenómeno relacionado con un brusco aumento del ritmo de acreción de materia sobre el agujero negro. Este aumento de brillo se produce en todas las

A large fraction of planetary nebulae (about 80%) are bipolar or elliptical rather than spherically symmetric. Modern theories invoke magnetic fields, among other causes, to explain the rich variety of aspherical components observed in planetary nebulae (PNe), as ejected matter is trapped along magnetic field lines. But, until recently, this idea was mostly a theoretical claim. But in 2005, Jordan et al. report the detection of kG magnetic fields in the central star of two non-spherical PNe, namely NGC1360 and LSS1362. They observed the circular polarization spectra of these stars with the

The proper characterization of the least massive population of the young Sigma Orionis star cluster is required to understand the form of the cluster mass function and its impact on our comprehension of the substellar formation processes. S Ori 70 (T5.5+/-1) and 73, two T-type cluster member candidates, are likely to have masses between 3 and 7 MJup if their age is 3 Myr. It awaits confirmation whether S Ori 73 has a methane atmosphere. We aim to: i) confirm the presence of methane absorption in S Ori 73 by performing methane imaging; ii) study S Ori 70 and 73 cluster membership via

The Kepler spacecraft is monitoring the brightness of more than 150,000 stars  in the constellations Cygnus, Lyra,  and Draco. The photometric time series with micromagnitude precision are excellent for the study of stellar oscillations. The oscillations lead to small changes in brightness and are caused by waves trapped inside the stars. The field of asteroseismology uses information from the stellar oscillations to infer information from the stellar internal structure. The delta Scuti and gamma Doradus stars are two classes of oscillating stars of spectral type A and F that are slightly