Search Publications
Effective temperatures of cataclysmic-variable white dwarfs as a probe of their evolution
Reichart, D. E.; Knigge, C.; Gänsicke, B. T. +29 more
We present HST spectroscopy for 45 cataclysmic variables (CVs), observed with HST/COS and HST/STIS. For 36 CVs, the white dwarf is recognisable through its broad Ly α absorption profile and we measure the white dwarf effective temperatures (Teff) by fitting the HST data assuming log g = 8.35, which corresponds to the average mass for CV…
Beyond the Kepler/K2 bright limit: variability in the seven brightest members of the Pleiades
Aigrain, S.; Grundahl, F.; Albrecht, S. +20 more
The most powerful tests of stellar models come from the brightest stars in the sky, for which complementary techniques, such as astrometry, asteroseismology, spectroscopy and interferometry, can be combined. The K2 mission is providing a unique opportunity to obtain high-precision photometric time series for bright stars along the ecliptic. Howeve…
Super-Eddington QSO RX J0439.6-5311 - II. Multiwavelength constraints on the global structure of the accretion flow
Done, Chris; Ward, Martin; Jin, Chichuan +1 more
We present a detailed multiwavelength study of an unobscured, highly super-Eddington Type-1 QSO RX J0439.6-5311. We combine the latest XMM-Newton observation with all archival data from infrared to hard X-rays. The optical spectrum is very similar to that of 1H 0707-495 in having extremely weak [O III] and strong Fe II emission lines, although the…
Discovery of a variable lead-rich hot subdwarf: UVO 0825+15
Reed, M. D.; Jeffery, C. S.; Woolf, V. M. +8 more
UVO 0825+15 is a hot bright helium-rich subdwarf which lies in K2 Field 5 and in a sample of intermediate helium-rich subdwarfs observed the Subaru High Dispersion Spectrograph. The K2 light curve shows low-amplitude variations, whilst the Subaru spectrum shows Pb IV absorption lines, indicative of a very high lead overabundance. UVO 0825+15 also …
The detection of variable radio emission from the fast rotating magnetic hot B-star HR\xA07355 and evidence for its X-ray aurorae
Umana, G.; Leone, F.; Ignace, R. +6 more
In this paper, we investigate the multiwavelength properties of the magnetic early B-type star HR 7355. We present its radio light curves at several frequencies, taken with the Jansky Very Large Array, and X-ray spectra, taken with the XMM-Newton X-ray telescope. Modelling of the radio light curves for the Stokes I and V provides a quantitative an…
The pulsating magnetosphere of the extremely slowly rotating magnetic β Cep star ξ1 CMa
Rivinius, Th.; Wade, G. A.; Neiner, C. +4 more
ξ1 CMa is a monoperiodically pulsating, magnetic β Cep star with magnetospheric X-ray emission that, uniquely amongst magnetic stars, is clearly modulated with the star's pulsation period. The rotational period Prot has yet to be identified, with multiple competing claims in the literature. We present an analysis of a large E…
Young LMC clusters: the role of red supergiants and multiple stellar populations in their integrated light and CMDs
Beasley, Michael A.; Vazdekis, Alexandre; Cerviño, Miguel +3 more
The optical integrated spectra of three Large Magellanic Cloud young stellar clusters (NGC 1984, NGC 1994 and NGC 2011) exhibit concave continua and prominent molecular bands which deviate significantly from the predictions of single stellar population (SSP) models. In order to understand the appearance of these spectra, we create a set of young s…
Quantitative spectroscopy of extreme helium stars Model atmospheres and a non-LTE abundance analysis of BD+10°2179
Butler, K.; Heber, U.; Przybilla, N. +3 more
Extreme helium stars (EHe stars) are hydrogen-deficient supergiants of spectral type A and B. They are believed to result from mergers in double degenerate systems. In this paper, we present a detailed quantitative non-LTE spectral analysis for BD+10°2179, a prototype of this rare class of stars, using UV-Visual Echelle Spectrograph and Fiber-fed …
Mid-infrared observations of O-type stars: spectral morphology
Bouret, J. -C.; Audard, M.; Lanz, T. +2 more
We present mid-infrared (mid-IR) observations for a sample of 16 O-type stars. The data were acquired with the NASA Spitzer Space Telescope, using the IRS instrument at moderate resolution (R ∼ 600), covering the range of ∼10-37 µm. Our sample includes early, mid and late O supergiants and dwarfs. We explore for the first time their mid-IR s…
Ultraviolet spectroscopy of the blue supergiant SBW1: the remarkably weak wind of a SN 1987A analogue
Smith, Nathan; France, Kevin; Groh, Jose H. +1 more
The Galactic blue supergiant SBW1 with its circumstellar ring nebula represents the best known analogue of the progenitor of SN 1987A. High-resolution imaging has shown Hα and infrared structures arising in an ionized flow that partly fills the ring's interior. To constrain the influence of the stellar wind on this structure, we obtained an ultrav…