References of "Gosset, Eric"
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See detailEvidence for a physically bound third component in HD 150136
Mahy, Laurent ULg; Gosset, Eric ULg; Sana, H et al

in Astronomy and Astrophysics (2012), 540

Context. HD 150136 is one of the nearest systems harbouring an O3 star. Although this system was considered for a long time as a binary, more recent investigations have suggested the possible existence of ... [more ▼]

Context. HD 150136 is one of the nearest systems harbouring an O3 star. Although this system was considered for a long time as a binary, more recent investigations have suggested the possible existence of a third component. <BR /> Aims: We present a detailed analysis of HD 150136 to test its triple nature. In addition, we investigate the physical properties of the individual components of this system. <BR /> Methods: We analysed high-resolution, high signal-to-noise data collected through multi-epoch runs spread over ten years. We applied a disentangling program to refine the radial velocities and to obtain the individual spectra of each star. With the radial velocities, we computed the orbital solution of the inner system, and we describe the main properties of the orbit of the outer star such as the preliminary mass ratio, the eccentricity, and the orbital-period range. With the individual spectra, we determined the stellar parameters of each star by means of the CMFGEN atmosphere code. <BR /> Results: We offer clear evidence that HD 150136 is a triple system composed of an O3V((f[SUP]∗[/SUP]))-3.5V((f[SUP]+[/SUP])), an O5.5-6V((f)), and an O6.5-7V((f)) star. The three stars are between 0-3 Myr old. We derive dynamical masses of about 64, 40, and 35 M[SUB]&sun;[/SUB] for the primary, the secondary and the third components by assuming an inclination of 49° (sin[SUP]3[/SUP]i = 0.43). It currently corresponds to one of the most massive systems in our galaxy. The third star moves with a period in the range of 2950 to 5500 d on an outer orbit with an eccentricity of at least 0.3. However, because of the long orbital period, our dataset is not sufficient to constrain the orbital solution of the tertiary component with high accuracy. <BR /> Conclusions: We confirm there is a tertiary star in the spectrum of HD 150136 and show that it is physically bound to the inner binary system. This discovery makes HD 150136 the first confirmed triple system with an O3 primary star. Table 1 is available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailAngular correlation functions of X-ray point-like sources in the full exposure XMM-LSS field
Elyiv, Andrii ULg; Clerc, N.; Plionis, M. et al

in Astronomy and Astrophysics (2012), 537

<BR /> Aims: Our aim is to study the large-scale structure of different types of AGN using the medium-deep XMM-LSS survey. <BR /> Methods: We measure the two-point angular correlation function of 5700 and ... [more ▼]

<BR /> Aims: Our aim is to study the large-scale structure of different types of AGN using the medium-deep XMM-LSS survey. <BR /> Methods: We measure the two-point angular correlation function of 5700 and 2500 X-ray point-like sources over the 11 sq. deg. XMM-LSS field in the soft (0.5-2 keV) and hard (2-10 keV) bands. For the conversion from the angular to the spatial correlation function we used the Limber integral equation and the luminosity-dependent density evolution model of the AGN X-ray luminosity function. <BR /> Results: We have found significant angular correlations with the power-law parameters γ = 1.81 ± 0.02, θ[SUB]0[/SUB] = 1.3'' ± 0.2'' for the soft, and γ = 2.00 ± 0.04, θ[SUB]0[/SUB] = 7.3'' ± 1.0'' for the hard bands. The amplitude of the correlation function w(θ) is higher in the hard than in the soft band for f[SUB]x[/SUB] ≲ 10[SUP]-14[/SUP] erg s[SUP]-1[/SUP] cm[SUP]-2[/SUP] and lower above this flux limit. We confirm that the clustering strength θ[SUB]0[/SUB] grows with the flux limit of the sample, a trend which is also present in the amplitude of the spatial correlation function, but only for the soft band. In the hard band, it remains almost constant with r[SUB]0[/SUB] ≃ 10h[SUP]-1[/SUP] Mpc, irrespective of the flux limit. Our analysis of AGN subsamples with different hardness ratios shows that the sources with a hard-spectrum are more clustered than soft-spectrum ones. This result may be a hint that the two main types of AGN populate different environments. Finally, we find that our clustering results correspond to an X-ray selected AGN bias factor of 2.5 for the soft band sources (at a median <inline-formula>bar{z} ≃ 1.1) and 3.3 for the hard band sources (at a median <inline-formula>bar{z} ≃ 1), which translates into a host dark matter halo mass of 10[SUP]13[/SUP]h[SUP]-1[/SUP]M[SUB]&sun;[/SUB] and 10[SUP]13.7[/SUP]h[SUP]-1[/SUP]M[SUB]&sun;[/SUB] for the soft and hard bands, respectively. This paper is dedicated to the memory of Olivier Garcet who has initiated the present work just before his sudden death. [less ▲]

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See detailVariability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150, and HD 46966
Blomme, R.; Mahy, Laurent ULg; Catala, C. et al

in Astronomy and Astrophysics (2011), 533

Context. The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric ... [more ▼]

Context. The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and time-coverage for a number of O-type stars. <BR /> Aims: We analyse the CoRoT data corresponding to three hot O-type stars, describing the properties of their light curves and search for pulsational frequencies, which we then compare to theoretical model predictions. <BR /> Methods: We determine the amplitude spectrum of the data, using the Lomb-Scargle and a multifrequency HMM-like technique. Frequencies are extracted by prewhitening, and their significance is evaluated under the assumption that the light curve is dominated by red noise. We search for harmonics, linear combinations, and regular spacings among these frequencies. We use simulations with the same time sampling as the data as a powerful tool to judge the significance of our results. From the theoretical point of view, we use the MAD non-adiabatic pulsation code to determine the expected frequencies of excited modes. <BR /> Results: A substantial number of frequencies is listed, but none can be convincingly identified as being connected to pulsations. The amplitude spectrum is dominated by red noise. Theoretical modelling shows that all three O-type stars can have excited modes, but the relation between the theoretical frequencies and the observed spectrum is not obvious. <BR /> Conclusions: The dominant red noise component in the hot O-type stars studied here clearly points to a different origin than the pulsations seen in cooler O stars. The physical cause of this red noise is unclear, but we speculate on the possibility of sub-surface convection, granulation, or stellar wind inhomogeneities being responsible. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany and Spain.Tables 2-4 are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/533/A4">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/533/A4</A> [less ▲]

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See detailThe massive star binary fraction in young open clusters - III. IC 2944 and the Cen OB2 association
Sana, H.; James, G.; Gosset, Eric ULg

in Monthly Notices of the Royal Astronomical Society (2011), 416

Using an extended set of multi-epoch high-resolution high signal-to-noise ratio optical spectra, we readdress the multiplicity properties of the O-type stars in IC 2944 and in the Cen OB2 association. We ... [more ▼]

Using an extended set of multi-epoch high-resolution high signal-to-noise ratio optical spectra, we readdress the multiplicity properties of the O-type stars in IC 2944 and in the Cen OB2 association. We present new evidence of binarity for five objects and we confirm the multiple nature of another two. We derive the first orbital solutions for HD 100099, HD 101436 and HD 101190 and we provide additional support for HD 101205 being a quadruple system. The minimal spectroscopic binary fraction in our sample is f[SUB]min[/SUB]= 0.57. Using numerical simulations, we show that the detection rate of our observational campaign is close to 90 per cent, leaving thus little room for undetected spectroscopic binary systems. The statistical properties of the O-star population in IC 2944 are similar, within the uncertainties, to the results obtained in the earlier papers in this series despite the fact that sample size effects limit the significance of the comparison. Using newly derived spectroscopic parallaxes, we reassess the distance to IC 2944 and obtained 2.3 ± 0.3 kpc, in agreement with previous studies. We also confirm that, as far as the O stars are concerned, the IC 2944 cluster is most likely a single entity. [less ▲]

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See detailHD 150136: towards one of the most massive systems?
Mahy, Laurent ULg; Gosset, Eric ULg; Sana, Hugues et al

in Neiner, Coralie; Wade, G.; Meynet, G. (Eds.) et al Active OB stars: structure, evolution, mass loss and critical limits (2011, July 01)

We present the preliminary results of an intensive monitoring devoted to HD 150136. Already quoted as an O3+O6 binary, we detected a third O-type component physically linked to the system, making it one ... [more ▼]

We present the preliminary results of an intensive monitoring devoted to HD 150136. Already quoted as an O3+O6 binary, we detected a third O-type component physically linked to the system, making it one of the nearest (1.3 kpc) most massive systems known until now (~134M[SUB]solar[/SUB]). To determine the physical parameters of this system, we applied a disentangling program to study individually the three components. It allows us to constrain their spectral types and to derive a new orbital solution for the short-period system. [less ▲]

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See detailInvestigating the X-ray emission from the massive WR+O binary WR 22 using 3D hydrodynamical models
Parkin, E. R.; Gosset, Eric ULg

in Astronomy and Astrophysics (2011), 530

<BR /> Aims: We examine the dependence of the wind-wind collision and subsequent X-ray emission from the massive WR+O star binary WR 22 on the acceleration of the stellar winds, radiative cooling, and ... [more ▼]

<BR /> Aims: We examine the dependence of the wind-wind collision and subsequent X-ray emission from the massive WR+O star binary WR 22 on the acceleration of the stellar winds, radiative cooling, and orbital motion. <BR /> Methods: Three dimensional (3D) adaptive-mesh refinement (AMR) simulations are presented that include radiative driving, gravity, optically-thin radiative cooling, and orbital motion. Simulations were performed with instantaneously accelerated and radiatively driven stellar winds. Radiative transfer calculations were performed on the simulation output to generate synthetic X-ray data, which are used to conduct a detailed comparison against observations. <BR /> Results: When instantaneously accelerated stellar winds are adopted in the simulation, a stable wind-wind collision region (WCR) is established at all orbital phases. In contrast, when the stellar winds are radiatively driven, and thus the acceleration regions of the winds are accounted for, the WCR is far more unstable. As the stars approach periastron, the ram pressure of the WR's wind overwhelms the O star's and, following a significant disruption of the shocks by non-linear thin-shell instabilities (NTSIs), the WCR collapses onto the O star. X-ray calculations reveal that when a stable WCR exists the models over-predict the observed X-ray flux by more than two orders of magnitude. The collapse of the WCR onto the O star substantially reduces the discrepancy in the 2-10keV flux to a factor of ≃ 6 at φ = 0.994. However, the observed spectrum is not well matched by the models. <BR /> Conclusions: We conclude that the agreement between the models and observations could be improved by increasing the ratio of the mass-loss rates in favour of the WR star to the extent that a normal wind ram pressure balance does not occur at any orbital phase, potentially leading to a sustained collapse of the WCR onto the O star. Radiative braking may then play a significant rôle for the WCR dynamics and resulting X-ray emission. [less ▲]

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See detailXMM-Newton observation of the enigmatic object WR 46
Gosset, Eric ULg; De Becker, Michaël ULg; Nazé, Yaël ULg et al

in Astronomy and Astrophysics (2011), 527

Aims: To further investigate the nature of the enigmatic object WR 46 and better understand the X-ray emission in massive stars and in their evolved descendants, we observed this variable object for more ... [more ▼]

Aims: To further investigate the nature of the enigmatic object WR 46 and better understand the X-ray emission in massive stars and in their evolved descendants, we observed this variable object for more than two of its supposed cycles. The X-ray emission characteristics are appropriate indicators of the difference between a genuine Wolf-Rayet star and a specimen of a super soft source as sometimes suggested in the literature. The X-ray emission analysis might contribute to understanding the origin of the emitting plasma (intrinsically shocked wind, magnetically confined wind, colliding winds, and accretion onto a white dwarf or a more compact object) and to substantiating the decision about the exact nature of the star. <BR /> Methods: The X-ray observations of WR 46 were performed with the XMM-Newton facility over an effective exposure time of about 70 ks. <BR /> Results: Both the X-ray luminosity of WR 46, typical of a Wolf-Rayet star, and the existence of a relatively hard component (including the Fe-K line) rule out the possibility that WR 46 could be classified as a super soft source, and instead favour the Wolf-Rayet hypothesis. The X-ray emission of the star turns out to be variable below 0.5 keV but constant at higher energies. The soft variability is associated to the Wolf-Rayet wind, but revealing its deep origin necessitates additional investigations. It is the first time that such a variability is reported for a Wolf-Rayet star. Indeed, the X-ray emission exhibits a single-wave variation with a typical timescale of 7.9 h which could be related to the period observed in the visible domain both in radial velocities (single-wave) and in photometry (double-wave). The global X-ray emission seems to be dominated by lines and is closely reproduced by a three-temperature, optically thin, thermal plasma model. The derived values are 0.1-0.2 keV, 0.6 keV, and ~4 keV, which indicates that a wide range of temperatures is actually present. The soft emission part could be related to a shocked-wind phenomenon. The hard tail of the spectrum cannot presently be explained by such an intrinsic phenomenon as a shocked wind and instead suggests there is a wind-wind collision zone, as does the relatively high L[SUB]X[/SUB]/L[SUB]bol[/SUB] ratio. We argue that this scenario implies the existence of an object farther away from the WN3 object than any possible companion in an orbit related to the short periodicity. Based on observations with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). [less ▲]

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See detailGaia spectroscopy: processing, performances and scientific returns
Katz, D.; Cropper, M.; Meynadier, F. et al

in EAS Publication Series (2011, February 01)

During the five years of the mission, the Gaia spectrograph, the Radial Velocity Spectrometer (RVS) will repeatedly survey the celestial sphere down to magnitude V ~ 17-18. This talk presents: (i) the ... [more ▼]

During the five years of the mission, the Gaia spectrograph, the Radial Velocity Spectrometer (RVS) will repeatedly survey the celestial sphere down to magnitude V ~ 17-18. This talk presents: (i) the system which is currently developed within the Gaia Data Processing and Analysis Consortium (DPAC) to reduce and calibrate the spectra and to derive the radial and rotational velocities, (ii) the RVS expected performances and (iii) scientific returns. [less ▲]

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See detailThe multiplicity of O-type stars in NGC 2244
Mahy, Laurent ULg; Rauw, Grégor ULg; Martins, F. et al

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

The investigation of the multiplicity of massive stars is crucial to determine a robust binary fraction but also for understanding the physical properties of these objects. In this contribution, we will ... [more ▼]

The investigation of the multiplicity of massive stars is crucial to determine a robust binary fraction but also for understanding the physical properties of these objects. In this contribution, we will present the main results from our long-term spectroscopic survey devoted to the young open cluster NGC 2244. We discuss the spectral classification, the projected rotational velocity (v sin{i}) and the multiplicity of O-stars. The stellar and wind parameters of each star, obtained using the CMFGEN atmosphere code, help us to better constrain the individual properties of these objects. Several of these stars were observed by the CoRoT satellite (SRa02) in the Asteroseismology channel. This intensive monitoring and the unprecedented quality of the light curves allow us to shed a new light on these objects. [less ▲]

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See detailPlaskett's star: analysis of the CoRoT photometric data
Mahy, Laurent ULg; Gosset, Eric ULg; Baudin, F. et al

in Astronomy and Astrophysics (2011), 525

Context. The second short run (SRa02) of the CoRoT space mission for asteroseismology was partly devoted to stars belonging to the Mon OB2 association. An intense monitoring has been performed on Plaskett ... [more ▼]

Context. The second short run (SRa02) of the CoRoT space mission for asteroseismology was partly devoted to stars belonging to the Mon OB2 association. An intense monitoring has been performed on Plaskett's star (HD 47129) and the unprecedented quality of the light curve allows us to shed new light on this very massive, non-eclipsing binary system. <BR /> Aims: We particularly aimed at detecting periodic variability that might be associated with pulsations or interactions between both components. We also searched for variations related to the orbital cycle that could help to constrain the inclination and the morphology of the binary system. <BR /> Methods: We applied an iterative Fourier-based prewhitening and a multiperiodic fitting procedure to analyse the time series and extract the frequencies of variations from the CoRoT light curve. We describe the noise properties to tentatively define an appropriate significance criterion and, in consequence, to only point out the peaks at a certain significance level. We also detect the variations related to the orbital motion and study them with the NIGHTFALL programme. <BR /> Results: The periodogram computed from Plaskett's star CoRoT light curve mainly exhibits a majority of peaks at low frequencies. Among these peaks, we highlight a list of 43 values, notably including two different sets of harmonic frequencies whose fundamental peaks are located at about 0.07 and 0.82 d[SUP]-1[/SUP]. The former represents the orbital frequency of the binary system, whilst the latter could probably be associated with non-radial pulsations. The study of the 0.07 d[SUP]-1[/SUP] variations reveals a hot spot most probably situated on the primary star and facing the secondary. <BR /> Conclusions: The investigation of this unique dataset constitutes a further step in the understanding of Plaskett's star. These results provide a first basis for future seismic modelling and put forward the probable existence of non-radial pulsations in Plaskett's star. Moreover, the fit of the orbital variations confirms the problem of the distance of this system which was already mentioned in previous works. A hot region between both components renders the determination of the inclination ambiguous. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany and Spain.Table 2 is only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detail3D modelling of the massive star binary systems Eta Carinae, WR 22, and WR 140
Parkin, E. R.; Pittard, J. M.; Corcoran, M. F. et al

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

Massive stars possess powerful stellar winds. Wind-wind collision in a massive star binary system generates a region of thermalized plasma which may emit prolifically at X-ray wavelengths. Results are ... [more ▼]

Massive stars possess powerful stellar winds. Wind-wind collision in a massive star binary system generates a region of thermalized plasma which may emit prolifically at X-ray wavelengths. Results are presented from 3D adaptive-mesh refinement (AMR) hydrodynamical models which include radiative cooling and the radiative driving of the stellar winds. The models provide an exceptional insight into the turbulent nature of the wind-wind interaction regions. The X-ray emission from the hydrodynamical models is then calculated, allowing detailed comparisons with observational data. Preliminary results from investigations of Eta Carinae, WR 22, and WR 140 are discussed. [less ▲]

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See detailSpectroscopic binaries as observed by the future Gaia space mission
Damerdji, Yassine ULg; Delchambre, Ludovic ULg; Morel, Thierry ULg et al

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

The future Gaia satellite will observe a large number of stars through its three main channels: astrometric, photometric and, for the brightest stars, spectroscopic. The satellite is equipped with the RVS ... [more ▼]

The future Gaia satellite will observe a large number of stars through its three main channels: astrometric, photometric and, for the brightest stars, spectroscopic. The satellite is equipped with the RVS spectrograph, which will provide medium-resolution spectra over a small wavelength range. These spectra should allow us to identify stars exhibiting a composite spectrum, either because of a chance alignment or a true binarity. We discuss the various aspects related to the data treatment of the binary candidates and describe the algorithms that are intended to be included in the processing pipeline. [less ▲]

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See detailA photometric study of the Carina nebula region around WR 22
Kumar, Brajesh ULg; Manfroid, Jean ULg; Gosset, Eric ULg et al

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

We performed the first photometric observations of a field situated around WR 22 in the Carina nebula region. We present and discuss the preliminary results of the study.

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See detailMassive binaries as seen with Gaia
Palate, Matthieu ULg; Rauw, Grégor ULg; Gosset, Eric ULg et al

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

Gaia, ESA's forthcoming astrometric observatory, will observe a billion stars of our Galaxy, among which thousands of high-mass stars. In this contribution, we study the capabilities of Gaia's ... [more ▼]

Gaia, ESA's forthcoming astrometric observatory, will observe a billion stars of our Galaxy, among which thousands of high-mass stars. In this contribution, we study the capabilities of Gaia's spectrometer (RVS) in the context of massive stars, especially the detectability of lower-mass companions to O-type stars. This preliminary study enables us to estimate to what extent Gaia will constrain the distribution of the physical and orbital parameters of massive binaries (luminosity, period, mass ratio, eccentricity...). [less ▲]

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See detailThe X-ray emission of the WR+O binary WR 79
Gosset, Eric ULg; Sana, Hugues; Rauw, Grégor ULg et al

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

In the framework of our multiwavelength study of the open cluster NGC 6231, we observed the colliding-wind WR+O binary WR 79 at six different epochs with the XMM-Newton observatory. These pointings offer ... [more ▼]

In the framework of our multiwavelength study of the open cluster NGC 6231, we observed the colliding-wind WR+O binary WR 79 at six different epochs with the XMM-Newton observatory. These pointings offer the possibility to study the X-ray spectrum of WR 79 and its possible variability. Our results are briefly discussed and compared with the X-ray characteristics of other similar objects. [less ▲]

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See detailA search for X-ray sources around WR 22 in the Carina region
Claeskens, Jean-François ULg; Gosset, Eric ULg; Nazé, Yaël ULg et al

in Astronomy and Astrophysics (2011), 525

We present the results of a deep search for X-ray sources in a circular field of 30' in diameter situated around WR 22 in the Carina region and observed with the XMM-Newton observatory. This field is ... [more ▼]

We present the results of a deep search for X-ray sources in a circular field of 30' in diameter situated around WR 22 in the Carina region and observed with the XMM-Newton observatory. This field is broadly located to the west of the main part of the Carina nebula. On the basis of six pointings (nominal exposure time: 10 ks each) centred on the WR+O binary star WR 22, we perform a survey with an effective exposure time of 68.8 ks. We introduce a catalogue of 43 bona-fide X-ray point sources, most of which were unknown before the XMM-Newton observations, and perform the first steps towards their identifications by cross-correlating the positions with optical/infrared catalogues. We investigated the possible variability of these sources in the X-ray domain and we extracted a few X-ray spectra for the brightest ones. A short description of the diffuse X-ray emission present in the region is also given. Based on observations with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). [less ▲]

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See detailMassive binaries as seen with GAIA
Palate, Matthieu ULg; Rauw, Grégor ULg; Gosset, Eric ULg et al

Poster (2010, July)

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See detailA New Investigation of the Binary HD 48099
Mahy, Laurent ULg; Rauw, Grégor ULg; Martins, F. et al

in Astrophysical Journal (2010), 708

With an orbital period of about 3.078 days, the double-lined spectroscopic binary HD 48099 is, until now, the only short-period O+O system known in the Mon OB2 association. Even though an orbital solution ... [more ▼]

With an orbital period of about 3.078 days, the double-lined spectroscopic binary HD 48099 is, until now, the only short-period O+O system known in the Mon OB2 association. Even though an orbital solution has already been derived for this system, few information are available about the individual stars. We present, in this paper, the results of a long-term spectroscopic campaign. We derive a new orbital solution and apply a disentangling method to recover the mean spectrum of each star. To improve our knowledge concerning both components, we determine their spectral classifications and their projected rotational velocities. We also constrain the main stellar parameters of both stars by using the CMFGEN atmosphere code and provide the wind properties for the primary star through the study of International Ultraviolet Explorer spectra. This investigation reveals that HD 48099 is an O5.5 V ((f)) + O9 V binary with M [SUB]1[/SUB]sin[SUP]3[/SUP] i = 0.70 M [SUB]sun[/SUB] and M [SUB]2[/SUB]sin[SUP]3[/SUP] i = 0.39 M [SUB]sun[/SUB], implying a rather low orbital inclination. This result, combined with both a large effective temperature and log g, suggests that the primary star (vsin i sime 91 km s[SUP]â 1[/SUP]) is actually a fast rotator with a strongly clumped wind and a nitrogen abundance of about 8 times the solar value. [less ▲]

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See detailHD 150136: towards one of the most massive systems?
Mahy, Laurent ULg; Gosset, Eric ULg; Rauw, Grégor ULg et al

Poster (2010)

The improvement of the astronomical instrumentation allowed scientists to develop new analysis techniques to investigate binary and multiple stars. In this context, we present the preliminary results of ... [more ▼]

The improvement of the astronomical instrumentation allowed scientists to develop new analysis techniques to investigate binary and multiple stars. In this context, we present the preliminary results of an intense monitoring devoted to the triple system, HD 150136. Supposed to be the nearest O3 star (1.3 kpc), this object is also composed of two other early O-type stars, making it one of the most massive systems known until now (~ 134Mʘ). This multiple star is a non-thermal radio emitter and presents a colliding wind interaction zone. To determine the physical parameters of this system, we applied a disentangling program to study individually the three components. It allows us to revise their spectral classification and to derive a new orbital solution for the short-period system but also the first one for the entire system. [less ▲]

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