Search Publications
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…
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 …
Calibration of the Swift-UVOT ultraviolet and visible grisms
Carter, M.; Mehdipour, M.; Brown, P. J. +16 more
We present the calibration of the Swift Ultraviolet and Optical Telescope (UVOT ) grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands, respectively. The UV grism covers the range λ1700-5000 Å with a spectral resolution (λ/Δλ) of 75 at λ2600 Å for source magnitudes of u=10-16 mag, while t…
The surface magnetic field and chemical abundance distributions of the B2V helium-strong star HD 184927
Marcolino, W.; Kochukhov, O.; Bohlender, D. +8 more
A new time series of high-resolution Stokes I and V spectra of the magnetic B2V star HD 184927 has been obtained in the context of the Magnetism in Massive Stars Large Program with an Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) spectropolarimeter at the Canada-France-Hawaii Telescope and dimaPol liquid crystal spectr…
Bias in C IV-based quasar black hole mass scaling relationships from reverberation mapped samples
Shang, Zhaohui; Brotherton, Michael S.; DiPompeo, M. A. +1 more
The masses of the black holes powering quasars represent a fundamental parameter of active galaxies. Estimates of quasar black hole masses using single-epoch spectra are quite uncertain, and require quantitative improvement. We recently identified a correction for C IV λ1549-based scaling relationships used to estimate quasar black hole masses tha…
Confirming HD 23478 as a new magnetic B star hosting an Hα-bright centrifugal magnetosphere
Wade, G. A.; Bohlender, D. A.; Neiner, C. +11 more
In this paper, we report 23 magnetic field measurements of the B3IV star HD 23478: 12 obtained from high-resolution Stokes V spectra using the ESPaDOnS (Canada-France-Hawaii Telescope) and Narval (Télescope Bernard Lyot) spectropolarimeters, and 11 from medium-resolution Stokes V spectra obtained with the DimaPol spectropolarimeter (Dominion Astro…
Spectral analysis of BD+30°623, the peculiar binary central star of the planetary nebula NGC 1514★
Montesinos, B.; Solano, E.; Ulla, A. +2 more
NGC 1514 is a complex planetary nebula with a peculiar binary central star (BD+30°623) consisting of a cool star and a hot companion. To date, the parameters of the two stars have not been firmly established. We present a detailed spectral analysis of BD+30°623 based on intermediate-resolution Calar Alto Faint Object Spectrograph optical spectra a…
The magnetic field and spectral variability of the He-weak star HR 2949
Stahl, O.; Rivinius, Th.; Wade, G. A. +6 more
We analyse a high-resolution spectropolarimetric data set collected for the He-weak B3p IV star HR 2949. The Zeeman effect is visible in the circularly polarized component of numerous spectral lines. The longitudinal magnetic field varies between approximately -650 and +150 G. The polar strength of the surface magnetic dipole is calculated to be 2…