The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and Hα at ˜1 arcsec angular resolution. Its footprint spans the Galactic latitude range -5o b +5° at all longitudes south of the celestial equator. Extensions around the Galactic Centre to Galactic latitudes ±10° bring

Context. The commonly used extinction laws of Cardelli et al. (1989, ApJ, 345, 245) have limitations that, among other issues, hamper the determination of the effective temperatures of O and early B stars from optical and near-infrared (NIR) photometry. Aims: We aim to develop a new family of extinction laws for 30 Doradus, check their general

Detailed spectral classifications are presented for 352 O-B0 stars in the VLT-FLAMES Tarantula Survey ESO Large Programme, of which 213 O-type are judged of sufficiently high quality for further morphological analysis. Among them, six subcategories of special interest are distinguished. (1) Several new examples of the earliest spectral types O2-O3

Context. O Vz stars, a subclass of O-type dwarfs characterized by having He ii λ4686 stronger in absorption than any other helium line in their blue-violet spectra, have been suggested to be on or near the zero-age main sequence (ZAMS). If their youth were confirmed, they would be key objects with which to advance our knowledge of the physical

We have identified ionized outflows in the narrow-line region of all but one Sloan Digital Sky Survey type 2 quasars (QSO2) at z≲0.1 (20/21, detection rate 95 per cent), implying that this is a ubiquitous phenomenon in this object class also at the lowest z. The outflowing gas has high densities (ne≳1000 cm-3) and covers a region the size of a few

The linear polarization signals produced by scattering processes in strong resonance lines are rich in information on the magnetic and thermal structure of the chromosphere and transition region of the Sun and of other stars. A correct modeling of these signals requires accounting for partial frequency redistribution effects, as well as for the