Search Publications
Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models
Przybilla, N.; Nieva, M. -F.
Context. Early B-type stars are ideal indicators for present-day cosmic abundances since they preserve their pristine abundances and typically do not migrate far beyond their birth environments over their short lifetimes, in contrast to older stars like the Sun. They are also unaffected by depletion onto dust grains, unlike the cold/warm interstel…
The warm gas atmosphere of the HD 100546 disk seen by Herschel. Evidence of a gas-rich, carbon-poor atmosphere?
van Dishoeck, E. F.; Bruderer, S.; Herczeg, G. J. +1 more
Context. With the Herschel Space Observatory, lines of simple molecules (C+, O, and high-J lines of CO, Jup ≳ 14) have been observed in the atmosphere of protoplanetary disks. When combined with ground-based data on [C i], all principle forms of carbon can be studied. These data allow us to test model predictions for the main…
The Galactic WC stars. Stellar parameters from spectral analyses indicate a new evolutionary sequence
Sander, A.; Hamann, W. -R.; Todt, H.
Context. The life cycles of massive stars from the main sequence to their explosion as supernovae or gamma ray bursts are not yet fully clear, and the empirical results from spectral analyses are partly in conflict with current evolutionary models. The spectral analysis of Wolf-Rayet stars requires the detailed modeling of expanding stellar atmosp…
Properties of Galactic early-type O-supergiants. A combined FUV-UV and optical analysis
Bouret, J. -C.; Hillier, D. J.; Fullerton, A. W. +1 more
Aims: We aim to constrain the properties and evolutionary status of early and mid-spectral type supergiants (from O4 to O7.5). These posses the highest mass-loss rates among the O stars, and exhibit conspicuous wind profiles.
Methods: Using the non-LTE wind code cmfgen we simultaneously analyzed the FUV-UV and optical spectral range to d…
Accretion-related properties of Herbig Ae/Be stars. Comparison with T Tauris
Eiroa, C.; Montesinos, B.; Mora, A. +4 more
Context. The mass accretion rate M⊙;acc) is a key parameter that has not accurately been determined for a wide sample of Herbig Ae/Be (HAeBe) stars until recently.
Aims: We look for trends relating M⊙acc and the stellar ages (t), spectral energy distributions (SEDs), and disk masses for a sample of 38 HAeBe stars, compar…
First spectro-interferometric survey of Be stars. I. Observations and constraints on the disk geometry and kinematics
Hofmann, K. -H.; Meilland, A.; Millour, F. +5 more
Context. Classical Be stars are hot non-supergiant stars surrounded by a gaseous circumstellar disk that is responsible for the observed infrared-excess and emission lines. The phenomena involved in the disk formation still remain highly debated.
Aims: To progress in the understanding of the physical process or processes responsible for the m…
Gas modelling in the disc of HD 163296
Pinte, C.; Ménard, F.; Duchêne, G. +19 more
We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of ~4 Myr, with evidence of a circumstellar disc extending out to ~540 AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determ…
A quantitative study of O stars in NGC 2244 and the Monoceros OB2 association
Martins, F.; Hillier, D. J.; Rauw, G. +1 more
Aims: Our goal is to determine the stellar and wind properties of seven O stars in the cluster NGC 2244 and three O stars in the OB association Mon OB2. These properties give us insight into the mass loss rates of O stars. They allow us to both check the validity of rotational mixing in massive stars and to better understand the effects of th…
Radiation-driven winds of hot luminous stars XVI. Expanding atmospheres of massive and very massive stars and the evolution of dense stellar clusters
Pauldrach, A. W. A.; Hoffmann, T. L.; Vanbeveren, D.
Context. Starbursts play an essential role in the evolution of galaxies. In these environments, massive stars, with their short lifetimes, are of particular importance. The stellar winds of massive stars significantly influence not only on their surroundings, but the associated mass loss also profoundly affects the evolution of the stars themselve…
Modelling of the ultraviolet and visual SED variability in the hot magnetic Ap star CU Virginis
Shulyak, D.; Krtička, J.; Lüftinger, T. +4 more
Context. The spectral energy distribution (SED) in chemically peculiar stars may be significantly affected by their abundance anomalies. The observed SED variations are usually assumed to be a result of inhomogeneous surface distribution of chemical elements, flux redistribution and stellar rotation. However, the direct evidence for this is still …