Results: This first paper reports on the data reduction of this unique dataset and provides a few preliminary results. On the one hand, analysis of EPIC low-resolution spectra shows the star to have a remarkably stable X-ray emission from one observation to the next. On the other hand, fitting by a wind model of individual line profiles recorded by RGS confirms the wavelength dependence of the line morphology. Based on observations collected with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).Table 1 is available in electronic form at http://www.aanda.org [less ▲]Detailed reference viewed: 45 (1 ULg) Le ciel pour tousNazé, Yaël Article for general public (2012)Detailed reference viewed: 46 (6 ULg) The first X-ray survey of Galactic Luminous Blue VariablesNazé, Yaël ; Rauw, Grégor ; Hutsemekers, Damien in Astronomy and Astrophysics (2012), 538Aims: The X-ray emission of massive stars has been studied when these objects are in their main-sequence phase, as well as in their Wolf-Rayet phase. However, the X-ray properties of the transitional ... [more ▼]Aims: The X-ray emission of massive stars has been studied when these objects are in their main-sequence phase, as well as in their Wolf-Rayet phase. However, the X-ray properties of the transitional Luminous Blue Variable (LBV) phase remain unknown. Methods: Using a dedicated but limited XMM survey as well as archival XMM and Chandra observations, we performed the first X-ray survey of LBVs: about half of the known LBVs or candidate LBVs are studied. Results: Apart from the well known X-ray sources eta Car and Cyg OB2 #12, four additional LBVs are detected in this survey, though some doubt remains on the association with the X-ray source for two of these. For the other LBVs, upper limits on the flux were derived, down to $\log[L_{\rm X}/L_{\rm BOL}]-9.4$ for PCyg. This variety in the strength of the X-ray emission is discussed, with particular emphasis on the potential influence of binarity. [less ▲]Detailed reference viewed: 36 (1 ULg) The spectral variability and magnetic field characteristics of the Of?p star HD 148937Wade, G. A.; Grunhut, J.; Gräfener, G. et alin Monthly Notices of the Royal Astronomical Society (2012), 419We report magnetic and spectroscopic observations and modelling of the Of?p star HD 148937 within the context of the Magnetism in Massive Stars (MiMeS) Large Program at the Canada-France-Hawaii Telescope ... [more ▼]We report magnetic and spectroscopic observations and modelling of the Of?p star HD 148937 within the context of the Magnetism in Massive Stars (MiMeS) Large Program at the Canada-France-Hawaii Telescope. 32 high signal-to-noise ratio circularly polarized (Stokes V) spectra and 13 unpolarized (Stokes I) spectra of HD 148937 were acquired in 2009 and 2010. A definite detection of a Stokes V Zeeman signature is obtained in the grand mean of all observations [in both least-squares deconvolved (LSD) mean profiles and individual spectral lines]. The longitudinal magnetic field inferred from the Stokes V LSD profiles is consistently negative, in contrast to the essentially zero field strength measured from the diagnostic null profiles. A period search of new and archival equivalent width measurements confirms the previously reported 7.03 d variability period. The variation of equivalent widths is not strictly periodic: we present evidence for evolution of the amount or distribution of circumstellar plasma. Interpreting the 7.03 d period as the stellar rotational period within the context of the oblique rotator paradigm, we have phased the equivalent widths and longitudinal field measurements. The longitudinal field measurements show a weak sinusoidal variation of constant sign, with extrema out of phase with the Hα variation by about 0.25 cycles. From our constraint on v sin i≤ 45 km s[SUP]-1[/SUP], we infer that the rotational axis inclination i≤ 30°. Modelling the longitudinal field phase variation directly, we obtain the magnetic obliquity β= 38[SUP]+17[/SUP][SUB]-28[/SUB]° and dipole polar intensity B[SUB]d[/SUB]= 1020[SUP]-380[/SUP][SUB]+310[/SUB] G. Simple modelling of the Hα equivalent width variation supports the derived geometry. The inferred magnetic configuration confirms the suggestion of Nazé et al., who proposed that the weaker variability of HD 148937 as compared to other members of this class is a consequence of the stellar geometry. Based on the derived magnetic properties and published wind characteristics, we find a wind magnetic confinement parameter η[SUB]*[/SUB]≃ 20 and rotation parameter W= 0.12, supporting a picture in which the Hα emission and other line variability have their origin in an oblique, rigidly rotating magnetospheric structure resulting from a magnetically channelled wind. [less ▲]Detailed reference viewed: 35 (0 ULg) (G)astronomie - Comète glacéeNazé, Yaël Article for general public (2012)Detailed reference viewed: 19 (2 ULg) Massive stars' nebulae, as seen through Herschel's eyesVamvatira-Nakou, Chloi ; Nazé, Yaël ; Hutsemekers, Damien et alPoster (2012)Detailed reference viewed: 66 (35 ULg) Cahier d'exploration du ciel II. Mesurer l'UniversNazé, Yaël Book published by Réjouisciences (2012)Detailed reference viewed: 28 (3 ULg) La cuisine du Cosmos. Traité de (G)astronomieNazé, Yaël Book published by Réjouisciences (2012)Detailed reference viewed: 42 (1 ULg) Cahier d'exploration du ciel I. découvrir l'Univers (réédition cahier 2009)Nazé, Yaël Book published by Réjouisciences (2012)Detailed reference viewed: 15 (1 ULg) Trois romans, trois visions de l’espace. Allers-retours entre science et littératureNazé, Yaël ; Dozo, Björn-Olav Article for general public (2012)Detailed reference viewed: 25 (4 ULg) First HARPSpol discoveries of magnetic fields in massive starsAlecian, E.; Kochukhov, O.; Neiner, C. et alin Astronomy and Astrophysics (2011), 536In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large ... [more ▼]In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large number of Southern massive OB stars in the field of the Galaxy and in many young clusters and associations. We report on the first discoveries of magnetic fields in two massive stars with HARPSpol - HD 130807 and HD 122451, and confirm the presence of a magnetic field at the surface of HD 105382 that was previously observed with a low spectral resolution device. The longitudinal magnetic field measurements strongly vary for HD 130807 from ~-100 G to ~700 G. Those of HD 122451 and HD 105382 are less variable with values ranging from ~-40 to -80 G, and from ~-300 to -600 G, respectively. The discovery and confirmation of three new magnetic massive stars, including at least two He-weak stars, is an important contribution to one of MiMeS objectives: the understanding of the origin of magnetic fields in massive stars and their impact on stellar structure and evolution. Based on observations collected at the European Southern Observatory, Chile (Program ID 187.D-0917). [less ▲]Detailed reference viewed: 24 (5 ULg) (G)astronomie - Stoemp célesteNazé, Yaël Article for general public (2011)Detailed reference viewed: 19 (4 ULg) A spectroscopic investigation of early-type stars in the young open cluster Westerlund 2Rauw, Grégor ; Sana, H.; Nazé, Yaël in Astronomy and Astrophysics (2011), 535Context. The distance of the very young open cluster Westerlund 2, which contains the very massive binary system WR 20a and is likely associated with a TeV source ... [more ▼]Context. The distance of the very young open cluster Westerlund 2, which contains the very massive binary system WR 20a and is likely associated with a TeV source, has been the subject of much debate.
Conclusions: The distance of Westerlund 2 is confirmed to be around 8 kpc as previously suggested based on the spectrophotometry of its population of O-type stars and the analysis of the light curve of WR 20a. Our results suggest that short-period binary systems are not likely to be common, at least not among the population of O-type stars in the cluster. Based on observations collected at the European Southern Observatory (Cerro Paranal, Chile).Appendix A is available in electronic form at http://www.aanda.org [less ▲]Detailed reference viewed: 21 (1 ULg) (G)astronomie - Tarte TitanNazé, Yaël Article for general public (2011)Detailed reference viewed: 21 (1 ULg) Confirmation of the magnetic oblique rotator model for the Of?p star HD 191612Wade, G. A.; Howarth, I. D.; Townsend, R. H. D. et alin Monthly Notices of the Royal Astronomical Society (2011), 416This paper reports high-precision Stokes V spectra of HD 191612 acquired using the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope, in the context of the Magnetism in Massive Stars ... [more ▼]This paper reports high-precision Stokes V spectra of HD 191612 acquired using the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope, in the context of the Magnetism in Massive Stars (MiMeS) Project. Using measurements of the equivalent width of the Hα line and radial velocities of various metallic lines, we have updated both the spectroscopic and orbital ephemerides of this star. We confirm the presence of a strong magnetic field in the photosphere of HD 191612, and detect its variability. We establish that the longitudinal field varies in a manner consistent with the spectroscopic period of 537.6 d, in an approximately sinusoidal fashion. The phases of minimum and maximum longitudinal field are, respectively, coincident with the phases of maximum and minimum Hα equivalent width and H[SUB]p[/SUB] magnitude. This demonstrates a firm connection between the magnetic field and the processes responsible for the line and continuum variability. Interpreting the variation of the longitudinal magnetic field within the context of the dipole oblique rotator model, and adopting an inclination i= 30° obtained assuming alignment of the orbital and rotational angular momenta, we obtain a best-fitting surface magnetic field model with obliquity β= 67°± 5° and polar strength B[SUB]d[/SUB]= 2450 ± 400 G. The inferred magnetic field strength implies an equatorial wind magnetic confinement parameter η[SUB]*[/SUB]≃ 50, supporting a picture in which the Hα emission and photometric variability have their origin in an oblique, rigidly rotating magnetospheric structure resulting from a magnetically channelled wind. This interpretation is supported by our successful Monte Carlo radiative transfer modelling of the photometric variation, which assumes the enhanced plasma densities in the magnetic equatorial plane above the star implied by such a picture, according to a geometry that is consistent with that derived from the magnetic field. Predictions of the continuum linear polarization resulting from Thompson scattering from the magnetospheric material indicate that the Stokes Q and U variations are highly sensitive to the magnetospheric geometry, and that expected amplitudes are in the range of current instrumentation. [less ▲]Detailed reference viewed: 45 (4 ULg) Les secrets de l'astrolabeNazé, Yaël Article for general public (2011)Detailed reference viewed: 42 (6 ULg) CCCP, une guerre stellaire plutot chaude - résuméNazé, Yaël Article for general public (2011)Detailed reference viewed: 12 (3 ULg) Dossier presse - expo les horlogers du cielChampenois, Carole ; Moreau, Didier ; Nazé, Yaël Diverse speeche and writing (2011)Detailed reference viewed: 58 (21 ULg) Of?p stars: a class of slowly rotating magnetic massive starsWade, Gregg A; Grunhut, Jason H; Marcolino, Wagner L F et alin Neiner, C.; Wade, G.; Meynet, G. (Eds.) et al Active OB stars: structure, evolution, mass loss and critical limits (2011, July 01)Only 5 Of?p stars have been identified in the Galaxy. Of these, 3 have been studied in detail, and within the past 5 years magnetic fields have been detected in each of them. The observed magnetic and ... [more ▼]Only 5 Of?p stars have been identified in the Galaxy. Of these, 3 have been studied in detail, and within the past 5 years magnetic fields have been detected in each of them. The observed magnetic and spectral characteristics are indicative of organised magnetic fields, likely of fossil origin, confining their supersonic stellar winds into dense, structured magnetospheres. The systematic detection of magnetic fields in these stars strongly suggests that the Of?p stars represent a general class of magnetic O-type stars. [less ▲]Detailed reference viewed: 45 (8 ULg) The surprising X-ray emission of Oe starsNazé, Yaël ; Rauw, Grégor ; ud-Doula, Asifin Neiner, Coralie; Wade, G.; Meynet, G. (Eds.) et al Active OB stars: structure, evolution, mass loss and critical limits (2011, July 01)Oe stars are thought to represent an extension of the Be phenomenon to higher temperatures. Dedicated XMM observations of HD 155806 revealed a surprising X-ray spectrum: soft character, absence of ... [more ▼]Oe stars are thought to represent an extension of the Be phenomenon to higher temperatures. Dedicated XMM observations of HD 155806 revealed a surprising X-ray spectrum: soft character, absence of overluminosity, broad X-ray lines. These properties are fully compatible with the wind-shock model, which usually explains the X-rays from normal', single O-type stars. In contrast, some other Oe/Be stars display a completely different behaviour at high energies. [less ▲]Detailed reference viewed: 14 (3 ULg)