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We performed a compilation of more than 1000 published spectra of H ii regions in spiral galaxies. The oxygen and nitrogen abundances in each H ii region were recomputed in a homogeneous way, using the P–method. The radial distributions of oxygen and nitrogen abundances were derived. The correlations between oxygen abundance and macroscopic properties are(More)
Context. Identifying the main processes of galaxy assembly at high redshifts is still a major issue to understand galaxy formation and evolution at early epochs in the history of the Universe. Aims. This work aims to provide a first insight into the dynamics and mass assembly of galaxies at redshifts 1.2 < z < 1.6, the early epoch just before the sharp(More)
To understand the evolution of galaxies, we need to know as accurately as possible how many galaxies were present in the Universe at different epochs. Galaxies in the young Universe have hitherto mainly been identified using their expected optical colours, but this leaves open the possibility that a significant population remains undetected because their(More)
Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the equations of cosmic expansion, accounting for about 75 per cent of the total energy density in the Universe. The simplest(More)
We report the detection of WC stars in five Wolf-Rayet (W-R) galaxies: He 2-10, NGC 3049, NGC 3125, NGC 5253 and Tol 89. The faint broad C iv λ5808 line requires sufficiently high S/N (> ∼ 40) to be detected explaining the non-detection of this WC feature in previous observations. From the measurement of W-R emission lines (N iii λ4640+C iii λ4650, He ii(More)
We present the gas-phase oxygen abundance (O/H) for a sample of 129 star-forming galaxies at intermediate redshifts (0.2 < z < 1.0). The sample selection, the spectroscopic observations (mainly with VLT/FORS) and associated data reduction, the photometric properties, the emission-line measurements, and the spectral classification are fully described in a(More)
We present here a compilation of PRONAOS-based results concerning the temperature dependence of the dust submillimeter spectral index , including data from Galactic cirrus, star-forming regions and a circum-stellar envelope. We observe large variations of the spectral index (from 0.8 to 2.4) in a wide range of temperatures (12 to 80 K). These spectral index(More)
We present spectroscopic observations of the central star clusters in NGC 5253 the aim of which is to search for WC stars. Our observations show the presence of Wolf-Rayet (WR) stars not only of WN but also of WC subtype in two star forming regions corresponding to the maximum optical and UV emission. The massive star population we derive is consistent with(More)
Context. We present the results of an imaging programme of distant galaxies (z ∼ 0.8) at high spatial resolution (∼ 0.1 ") aiming at studying their morphological evolution. We observed 7 fields of 1 ′ × 1 ′ with the NACO Adaptive Optics system (VLT) in Ks (2.16µm) band with typical V ∼ 14 guide stars and 3h integration time per field. Observed fields are(More)