Search Publications
Escape of Lyman continuum radiation from local galaxies. Detection of leakage from the young starburst Tol 1247-232
Hayes, M.; Zackrisson, E.; Leitet, E. +2 more
Context. It has been suggested that the escape fraction of hydrogen ionizing photons (fesc) from galaxies is evolving with time, but the picture is far from clear. While evidence for significant escape fractions has been found at high redshifts in several studies, the picture looks different in the closer universe. The lack of local det…
The VLT-FLAMES Tarantula Survey. XI. A census of the hot luminous stars and their feedback in 30 Doradus
van Loon, J. Th.; Crowther, P. A.; Herrero, A. +16 more
Context. The VLT-FLAMES Tarantula Survey has an extensive view of the copious number of massive stars in the 30 Doradus (30 Dor) star forming region of the Large Magellanic Cloud. These stars play a crucial role in our understanding of the stellar feedback in more distant, unresolved star forming regions.
Aims: The first comprehensive census …
Macroclumping as solution of the discrepancy between Hα and P v mass loss diagnostics for O-type stars
Hamann, W. -R.; Oskinova, L. M.; Aret, A. +3 more
Context. Recent studies of O-type stars have demonstrated that discrepant mass-loss rates are obtained when different diagnostic methods are employed. Fitting the unsaturated UV resonance lines (e.g., P v) gives drastically lower values than obtained from the Hα emission. Wind inhomogeneity (so-called "clumping") may be the main cause of this disc…
The spectroscopic evolution of the γ-ray emitting classical nova Nova Mon 2012. I. Implications for the ONe subclass of classical novae
Cheung, C. C.; Shore, S. N.; Starrfield, S. +4 more
Aims: Among the classical novae, the ONe subgroup, distinguished by their large overabundance of neon, are thought to occur on the most massive white dwarfs. Nova Mon 2012 was the first classical nova to be detected as a high energy γ-ray transient, by Fermi-LAT, before its optical discovery. The first optical spectra obtained about 55 days a…
Analysis of far-UV data of central stars of planetary nebulae: Occurrence and variability of stellar winds
Guerrero, M. A.; De Marco, O.
The occurrence of stellar wind in the central star of a planetary nebula (CSPN) can be revealed by the presence of P Cygni profiles of high-excitation lines overimposed on its stellar continuum. We examined the entire Far-Ultraviolet Spectroscopic Explorer (FUSE) archive and merged all useful spectroscopic observations of CSPNe to produce the high…
Discovery of the magnetic field in the pulsating B star β Cephei
Talavera, A.; Donati, J. -F.; Kaper, L. +17 more
Context. Although the star itself is not helium enriched, the periodicity and the variability in the UV wind lines of the pulsating B1 IV star β Cephei are similar to what is observed in magnetic helium-peculiar B stars, suggesting that β Cep is magnetic.
Aims: We searched for a magnetic field using high-resolution spectropolarimetry. From UV…
Vertical broad-line region structure in nearby active galactic nuclei
Kollatschny, W.; Zetzl, M.
Context. Broad emission lines are emitted in the surroundings of supermassive black holes in the centers of active galactic nuclei (AGN). This region is spatially not resolved.
Aims: We intend to get information on the structure and geometry of this broad emitting line region based on line profile observations.
Methods: We model the rota…
Discovery of a magnetic field in the CoRoT hybrid B-type pulsator HD 43317
Neiner, C.; Briquet, M.; Pápics, P. I. +2 more
Context. A promising way of testing the impact of a magnetic field on internal mixing (core overshooting, internal rotation) in main-sequence B-type stars is to perform asteroseismic studies of a sample of magnetic pulsators.
Aims: The CoRoT satellite revealed that the B3IV star HD 43317 is a hybrid SPB/β Cep-type pulsator that has a wealth o…
Evidence of quasi-chemically homogeneous evolution of massive stars up to solar metallicity
Martins, F.; Mahy, L.; Russeil, D. +1 more
Context. Long soft gamma-ray bursts (LGRBs) are usually associated with the death of the most massive stars. A large amount of core angular momentum in the phases preceding the explosion is required to form LGRBs. A very high initial rotational velocity can provide this angular momentum. This velocity strongly influences the way the star evolves: …
A self-consistent chemically stratified atmosphere model for the roAp star 10 Aquilae
Shulyak, D.; Kochukhov, O.; Weiss, W. +3 more
Context. Chemically peculiar A-type (Ap) stars are a subgroup of the CP2 stars that exhibit anomalous overabundances of numerous elements, e.g. Fe, Cr, Sr, and rare earth elements. The pulsating subgroup of Ap stars, the roAp stars, present ideal laboratories to observe and model pulsational signatures, as well as the interplay of the pulsations w…