References of "Nazé, Yaël"
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See detailLes couleurs de l'Univers
Nazé, Yaël ULg

Book (2005)

à quoi ressemble la Voie lactée dans l'ultraviolet ? Que cachent les nuages de poussière qui voilent des parties entières du ciel ? Avec la découverte des ondes électromagnétiques (ondes radio ... [more ▼]

à quoi ressemble la Voie lactée dans l'ultraviolet ? Que cachent les nuages de poussière qui voilent des parties entières du ciel ? Avec la découverte des ondes électromagnétiques (ondes radio, ultraviolet, infrarouge, rayons X, gamma), le ciel s'est teinté de nouvelles couleurs, changeant totalement d'aspect, jusqu'à révéler des phénomènes d'une violence insoupçonnée. Les télescopes du monde entier obtiennent maintenant des images d'un univers inconnu que l'auteur nous apprend à comprendre. Riche en anecdotes parfois cocasses sur des découvertes qui doivent parfois au hasard ou Ãà la persévérance obstinée de chercheurs, le livre invite le lecteur à découvrir un monde invisible à l'oeil. Des mystérieux quasars au rayonnement cosmologique, c'est à un voyage au fil de ce nouvel arc-en-ciel que nous convie l'auteur. [less ▲]

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See detailVision cosmique: le futur de l'espace européen
Nazé, Yaël ULg

Article for general public (2005)

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See detailExobiologie et complexité
Javaux, Emmanuelle ULg; Nazé, Yaël ULg

Article for general public (2005)

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See detailAstrobiologie et exploration du système solaire
Javaux, Emmanuelle ULg; Lebreton, Jean-Pierre; Chicarro, Augustin et al

Conference given outside the academic context (2005)

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See detailNous avons lu pour vous
Nazé, Yaël ULg

Article for general public (2005)

La Voie Lactée, Chaberlot, F.

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See detailOptical spectroscopy of X-Mega targets - V. The spectroscopic binary HD 93161 A and its visual companion HD 93161 B
Nazé, Yaël ULg; Antokhin, I. I.; Sana, H. et al

in Monthly Notices of the Royal Astronomical Society (2005), 359(2), 688-698

We present the analysis of an extensive set of high-resolution spectroscopic observations of HD 93161, a visual binary with a separation of 2 arcsec. HD 93161 A is a spectroscopic binary, with both ... [more ▼]

We present the analysis of an extensive set of high-resolution spectroscopic observations of HD 93161, a visual binary with a separation of 2 arcsec. HD 93161 A is a spectroscopic binary, with both components clearly detected throughout the orbit. The primary star is most probably of spectral type O8V, while the secondary is likely an O9V. We obtain the first orbital solution for this system, characterized by a period of 8.566 +/- 0.004 d. The minimum masses of the primary and secondary stars are 22.2 +/- 0.6 and 17.0 +/- 0.4 M-., respectively. These values are quite large, suggesting a high inclination of the orbit. The second object, HD 93161 B, displays an O6.5V(f) spectral type and is thus slightly hotter than its neighbour. This star is at first sight single but presents radial velocity variations. Finally, we study HD 93161 in the X-ray domain. No significant variability is detected. The X-ray spectrum is well described by a 2T model with kT(1) similar to 0.3 keV and kT(2) similar to 0.7 keV. The X-ray luminosity is rather moderate, without any large emission excess imputable to a wind interaction. [less ▲]

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See detailSous le vent des étoiles massives
Nazé, Yaël ULg

Article for general public (2005)

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See detailRendez-vous des mondes lointains
Nazé, Yaël ULg

Article for general public (2005)

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See detailA la recherche du neutrino perdu
Nazé, Yaël ULg

Article for general public (2005)

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See detailThe spectrum of the very massive binary system WR20a (WN6ha+WN6ha): Fundamental parameters and wind interactions
Rauw, Grégor ULg; Crowther, P. A.; De Becker, Michaël ULg et al

in Astronomy and Astrophysics (2005), 432(3), 985-998

We analyse the optical spectrum of the very massive binary system WR20a (WN6ha + WN6ha). The most prominent emission lines, Halpha and He II lambda4686, display strong phase-locked profile variability ... [more ▼]

We analyse the optical spectrum of the very massive binary system WR20a (WN6ha + WN6ha). The most prominent emission lines, Halpha and He II lambda4686, display strong phase-locked profile variability. From the variations of their equivalent widths and from a tomographic analysis, we find that part of the line emission probably arises in a wind interaction region between the stars. Our analysis of the optical spectrum of WR20a indicates a reddening of A(nu) similar or equal to 6.0 mag and a distance of similar to 7.9 kpc, suggesting that the star actually belongs to the open cluster Westerlund 2. The location of the system at similar to 1.1 pc from the cluster core could indicate that WR20a was gently ejected from the core via dynamical interactions. Using a non-LTE model atmosphere code, we derive the fundamental parameters of each component: T-eff = 43 000 +/- 2000 K, log L-bol/ L-. similar or equal to 6.0, (M) over dot = 8.5 x 10(-6) M-. yr(-1) (assuming a clumped wind with a volume filling factor f = 0.1). Nitrogen is enhanced in the atmospheres of the components of WR20a, while carbon is definitely depleted. Finally, the position of the binary components in the Hertzsprung-Russell diagram suggests that they are core hydrogen burning stars in a pre-LBV stage and their current atmospheric chemical composition probably results from rotational mixing that might be enhanced in a close binary compared to a single star of same age. [less ▲]

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See detailLes secrets du pendule
Nazé, Yaël ULg

Article for general public (2005)

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See detailBulles célestes
Nazé, Yaël ULg

Article for general public (2005)

See detailLes Belges vibrent pour les étoiles
Nazé, Yaël ULg

Article for general public (2005)

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See detailAn XMM-Newton look at the Wolf-Rayet star WR 40 - The star itself, its nebula and its neighbours
Gosset, Eric ULg; Nazé, Yaël ULg; Claeskens, Jean-François ULg et al

in Astronomy and Astrophysics (2005), 429(2), 685-704

We present the results of an XMM-Newton observation of the field of the Wolf-Rayet star WR 40. Despite a nominal exposure of 20 ks and the high sensitivity of the satellite, the star itself is not ... [more ▼]

We present the results of an XMM-Newton observation of the field of the Wolf-Rayet star WR 40. Despite a nominal exposure of 20 ks and the high sensitivity of the satellite, the star itself is not detected: we thus derive an upper limit on its X-ray flux and luminosity. Joining this result to recent reports of a non-detection of some WC stars, we suggest that the X-ray emission from single normal Wolf-Rayet stars could often be insignificant despite remarkable instabilities in the wind. On the basis of a simple modelling of the opacity of the Wolf-Rayet wind of WR 40, we show that any X-ray emission generated in the particular zone where the shocks are supposed to be numerous will indeed have little chance to emerge from the dense wind of the Wolf-Rayet star. We also report the non-detection of the ejecta nebula RCW 58 surrounding WR 40. Concerning the field around these objects, we detected 33 X-ray sources, most of them previously unknown: we establish a catalog of these sources and cross-correlate it with catalogs of optical/infrared sources. [less ▲]

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See detailFrédéric Chaberlot, La Voie Lactée: histoire des conceptions et des modèles de notre Galaxie des temps anciens aux années 1930, Bibliographie critique
Nazé, Yaël ULg

in Archives Internationales d'Histoire des Sciences (2005), (154), 302-302

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See detailVibrato, ma non troppo.
Nazé, Yaël ULg

Article for general public (2005)

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See detailA period and a prediction for the Of ? p spectrum alternator HD 191612
Walborn, Nolan R.; Howarth, Ian D.; Rauw, Grégor ULg et al

in Astrophysical Journal (2004), 617(1, Part 2), 61-64

The observational picture of the enigmatic O-type spectrum variable HD 191612 has been sharpened substantially. A symmetrical, low-amplitude light curve with a period near 540 days has recently been ... [more ▼]

The observational picture of the enigmatic O-type spectrum variable HD 191612 has been sharpened substantially. A symmetrical, low-amplitude light curve with a period near 540 days has recently been reported from Hipparcos photometry. This period satisfies all of the spectroscopy since at least 1982, including extensive new observations during 2003 and 2004, and it has predicted the next transition during 2004 September - October. Measurements of the Ha equivalent width reveal a sharp emission peak in the phase diagram, in contrast to the apparently sinusoidal light curve. The He II absorption-line strength is essentially constant, while He I varies strongly, possibly filled in by emission in the O6 state, thus producing the apparent spectral type variations. The O8 state appears to be the "normal" one. Two intermediate O7 observations have been obtained, which fall at the expected phases, but these are the only modern observations of the transitions so far. The period is too long for rotation or pulsation; although there is no direct evidence as yet for a companion, a model in which tidally induced oscillations drive an enhanced wind near periastron of an eccentric orbit appears promising. Further observations during the now predictable transitions may provide a critical test. Ultraviolet and X-ray observations during both states will likely also prove illuminating. [less ▲]

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See detailRendez-vous avec Vénus (II)
Nazé, Yaël ULg

Article for general public (2004)

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See detailMystery Star 1054
Nazé, Yaël ULg

Article for general public (2004)

It all began like any ordinary day. But suddenly, the sky changed with the appearance of a new star. Men and women raised their heads, shaking with fear. The sky should not change, they cried---this must ... [more ▼]

It all began like any ordinary day. But suddenly, the sky changed with the appearance of a new star. Men and women raised their heads, shaking with fear. The sky should not change, they cried---this must be a sign of the gods! We are doomed: this guest in our sky can only bring plague and disaster. [less ▲]

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See detailLes amas globulaires
Nazé, Yaël ULg

Article for general public (2004)

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