Search Publications
Wolf-Rayet stars in the Small Magellanic Cloud. I. Analysis of the single WN stars
Sander, A.; Hamann, W. -R.; Shenar, T. +3 more
Context. Wolf-Rayet (WR) stars have a severe impact on their environments owing to their strong ionizing radiation fields and powerful stellar winds. Since these winds are considered to be driven by radiation pressure, it is theoretically expected that the degree of the wind mass-loss depends on the initial metallicity of WR stars.
Aims: Foll…
C III] Emission in Star-forming Galaxies Near and Far
Dahle, H.; Rigby, J. R.; Bayliss, M. B. +5 more
We measure [C iii] 1907, C iii] 1909 Å emission lines in 11 gravitationally lensed star-forming galaxies at z ∼ 1.6-3, finding much lower equivalent widths than previously reported for fainter lensed galaxies. While it is not yet clear what causes some galaxies to be strong C iii] emitters, C iii] emission is not a universal property of distant st…
A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. IV. A Multiwavelength, Non-LTE Spectroscopic Analysis
Corcoran, M. F.; Hamann, W. -R.; Nazé, Y. +13 more
Eclipsing systems of massive stars allow one to explore the properties of their components in great detail. We perform a multi-wavelength, non-LTE analysis of the three components of the massive multiple system δ Ori A, focusing on the fundamental stellar properties, stellar winds, and X-ray characteristics of the system. The primary’s distance-in…
Revisiting the rigidly rotating magnetosphere model for σ Ori E - II. Magnetic Doppler imaging, arbitrary field RRM, and light variability
Owocki, S. P.; Wade, G. A.; Kochukhov, O. +6 more
The initial success of the Rigidly Rotating Magnetosphere (RRM) model application to the B2Vp star σ Ori E by Townsend, Owocki & Groote triggered a renewed era of observational monitoring of this archetypal object. We utilize high-resolution spectropolarimetry and the magnetic Doppler imaging (MDI) technique to simultaneously determine the mag…
Spectral and spatial imaging of the Be+sdO binary ϕ Persei
Berio, P.; Meilland, A.; Millour, F. +25 more
Aims: The rapidly rotating Be star
New light on Galactic post-asymptotic giant branch stars - I. First distance catalogue
Parker, Quentin A.; Vickers, Shane B.; Frew, David J. +1 more
We have commenced a detailed analysis of the known sample of Galactic post-asymptotic giant branch (PAGB) objects compiled in the Toruń catalogue of Szczerba et al., and present, for the first time, homogeneously derived distance determinations for the 209 likely and 87 possible catalogued PAGB stars from that compilation. Knowing distances are es…
New binaries among UV-selected, hot subdwarf stars and population properties
Buckley, D. A. H.; Vennes, S.; Németh, P. +4 more
We have measured the orbital parameters of seven close binaries, including six new objects, in a radial velocity survey of 38 objects comprising a hot subdwarf star with orbital periods ranging from ∼0.17 to 3 d. One new system, GALEX J2205-3141, shows reflection on an M dwarf companion. Three other objects show significant short-period variations…
No breakdown of the radiatively driven wind theory in low-metallicity environments
Bouret, J. -C.; Martins, F.; Hillier, D. J. +3 more
We present a spectroscopic analysis of Hubble Space Telescope/Cosmic Origins Spectrograph observations of three massive stars in the low metallicity dwarf galaxies IC 1613 and WLM. These stars, were previously observed with Very Large Telescope (VLT)/X-shooter by Tramper et al., who claimed that their mass-loss rates are higher than expected from …
A Light Curve Analysis of Classical Novae: Free-free Emission versus Photospheric Emission
Kato, Mariko; Hachisu, Izumi
We analyzed light curves of seven relatively slower novae, PW Vul, V705 Cas, GQ Mus, RR Pic, V5558 Sgr, HR Del, and V723 Cas, based on an optically thick wind theory of nova outbursts. For fast novae, free-free emission dominates the spectrum in optical bands rather than photospheric emission, and nova optical light curves follow the universal dec…
Non-conservative evolution in Algols: where is the matter?
Baes, M.; Jorissen, A.; Siess, L. +3 more
Context. There is indirect evidence of non-conservative evolutions in Algols. However, the systemic mass-loss rate is poorly constrained by observations and generally set as a free parameter in binary-star evolution simulations. Moreover, systemic mass loss may lead to observational signatures that still need to be found.
Aims: Within the "ho…