Search Publications
The Supernova Legacy Survey 3-year sample: Type Ia supernovae photometric distances and cosmological constraints
Sullivan, M.; Lidman, C.; González-Gaitán, S. +31 more
Aims: We present photometric properties and distance measurements of 252 high redshift Type Ia supernovae (0.15 < z < 1.1) discovered during the first three years of the Supernova Legacy Survey (SNLS). These events were detected and their multi-colour light curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawa…
The Effect of a Strong Stellar Flare on the Atmospheric Chemistry of an Earth-like Planet Orbiting an M Dwarf
Walkowicz, Lucianne M.; Segura, Antígona; Hawley, Suzanne +2 more
Main sequence M stars pose an interesting problem for astrobiology: their abundance in our galaxy makes them likely targets in the hunt for habitable planets, but their strong chromospheric activity produces high-energy radiation and charged particles that may be detrimental to life. We studied the impact of the 1985 April 12 flare from the M dwar…
A Library of Theoretical Ultraviolet Spectra of Massive, Hot Stars for Evolutionary Synthesis
Pettini, Max; Leitherer, Claus; Bresolin, Fabio +5 more
We computed a comprehensive set of theoretical ultraviolet spectra of hot, massive stars with the radiation-hydrodynamics code WM-Basic. This model atmosphere and spectral synthesis code is optimized for computing the strong P Cygni type lines originating in the winds of hot stars, which are the strongest features in the ultraviolet spectral regio…
Accurate fundamental parameters for 23 bright solar-type stars
Butler, R. P.; Carrier, F.; Lo Curto, G. +7 more
We combine results from interferometry, asteroseismology and spectroscopy to determine accurate fundamental parameters of 23 bright solar-type stars, from spectral type F5 to K2 and luminosity classes III-V. For some stars we can use direct techniques to determine the mass, radius, luminosity and effective temperature, and we compare with indirect…
Deviations from a uniform period spacing of gravity modes in a massive star
Aerts, Conny; Miglio, Andrea; Bloemen, Steven +13 more
The life of a star is dominantly determined by the physical processes in the stellar interior. Unfortunately, we still have a poor understanding of how the stellar gas mixes near the stellar core, preventing precise predictions of stellar evolution. The unknown nature of the mixing processes as well as the extent of the central mixed region is par…
Detection of a magnetic field on HD108: clues to extreme magnetic braking and the Of?p phenomenon
Bouret, J. -C.; Martins, F.; Donati, J. -F. +5 more
We report the detection of a magnetic field on the Of?p star HD108. Spectropolarimetric observations conducted in 2007, 2008 and 2009, respectively, with NARVAL@Télescope Bernard Lyot (TBL) and Echelle SpectroPolarimetric Device for the Observation of Stars at Canada-France-Hawaii Telescope (ESPaDOnS@CFHT) reveal a clear Zeeman signature in the av…
Chemical composition of A and F dwarfs members of the Hyades open cluster
Fossati, L.; Gebran, M.; Monier, R. +1 more
Aims: Abundances of 15 chemical elements have been derived for 28 F and 16 A stars members of the Hyades open cluster in order to set constraints on self-consistent evolutionary models that include radiative and turbulent diffusion.
Methods: A spectral synthesis, iterative procedure was applied to derive the abundances from selected high…
New Insights into the Problem of the Surface Gravity Distribution of Cool DA White Dwarfs
Tremblay, P. -E.; Bergeron, P.; Kalirai, J. S. +1 more
We review at length the longstanding problem in the spectroscopic analysis of cool hydrogen-line (DA) white dwarfs (T eff< 13,000 K) where gravities are significantly higher than those found in hotter DA stars. The first solution that has been proposed for this problem is a mild and systematic helium contamination from convective mix…
Signature of wide-spread clumping in B supergiant winds
Prinja, R. K.; Massa, D. L.
Aims: We seek to establish additional observational signatures of the effects of clumping in OB star winds. The action of clumping on strategic wind-formed spectral lines is tested to steer the development of models for clumped winds and thus improve the reliability of mass-loss determinations for massive stars.
Methods: The Siiv λλ1400 …
The extrasolar planet Gliese 581d: a potentially habitable planet?
Rauer, H.; von Paris, P.; Grenfell, J. L. +6 more
Aims: The planetary system around the M star Gliese 581 contains at least three close-in potentially low-mass planets, Gl 581c, d, and e. In order to address the question of the habitability of Gl 581d, we performed detailed atmospheric modeling studies for several planetary scenarios.
Methods: A 1D radiative-convective model was used to…