Based on the best observations of extragalactic H II regions of low metallicity available in the literature we redetermine the primordial helium abundance, Y[p]...

The abundance of O in planetary nebulae (PNe) has been historically used as a metallicity indicator of the interstellar medium (ISM), where they originated; e.g...

We have used images from the Advanced Camera for Surveys on the Hubble Space Telescope in Hα, and in the neighboring continuum, to produce flux-calibrated...

We present a systematic study of the radial brightness profiles in H alpha of a set of H ii regions in 6 late-type spiral galaxies, complete down to stated...

The study of radial metallicity gradients in the disc of the Milky Way is a powerful tool to understand the mechamisms that have been acting in the formation...

We present heliocentric radial velocities for a large number of emission lines covering all the optical spectral range for two slit positions of the Galactic H...

We have derived a primordial helium abundance of Yp=0.2477+/-0.0029, based on new atomic physics computations of the recombination coefficients of He I and of...

We present spectra obtained with the 10.4 m Gran Telescopio Canarias telescope of 13 Galactic H II regions, most of them of very low ionization degree. The...

With the aim of investigating galaxies with two strong simultaneous starbursts, we have extracted a sample of galaxies with double-peaked emission lines in...