References of "Rauw, Grégor"
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See detailMESS (Mass-loss of Evolved StarS), a Herschel Key Program
Groenewegen, M. A. T.; Waelkens, C.; Barlow, M. J. et al

in Astronomy and Astrophysics (2011), 526

MESS (Mass-loss of Evolved StarS) is a Guaranteed Time Key Program that uses the PACS and SPIRE instruments on board the Herschel Space Observatory to observe a representative sample of evolved stars ... [more ▼]

MESS (Mass-loss of Evolved StarS) is a Guaranteed Time Key Program that uses the PACS and SPIRE instruments on board the Herschel Space Observatory to observe a representative sample of evolved stars, that include asymptotic giant branch (AGB) and post-AGB stars, planetary nebulae and red supergiants, as well as luminous blue variables, Wolf-Rayet stars and supernova remnants. In total, of order 150 objects are observed in imaging and about 50 objects in spectroscopy. This paper describes the target selection and target list, and the observing strategy. Key science projects are described, and illustrated using results obtained during Herschel's science demonstration phase. Aperture photometry is given for the 70 AGB and post-AGB stars observed up to October 17, 2010, which constitutes the largest single uniform database of far-IR and sub-mm fluxes for late-type stars. [less ▲]

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See detailHerschel-PACS observations of Nebulae Ejected by Massive Stars
Vamvatira Nakou, Chloi ULg; Royer, Pierre; Hutsemekers, Damien ULg et al

in Bulletin de la Société Royale des Sciences de Liège (2011), 80

The study of the nebulae ejected from Luminous Blue Variables and the circumstellar bubbles around Wolf-Rayet stars, which radiate strongly in the infrared due to the heating of dust, is crucial for the ... [more ▼]

The study of the nebulae ejected from Luminous Blue Variables and the circumstellar bubbles around Wolf-Rayet stars, which radiate strongly in the infrared due to the heating of dust, is crucial for the understanding of the massive stars evolution. With Herschel we are able to observe these objects in the far-infrared region. In the context of the Mass-loss from Evolved StarS guaranteed time key program, we obtained imaging and spectroscopic observations of nebulae associated with Luminous Blue Variable and Wolf-Rayet stars using PACS, one of the three instruments on-board Herschel. A description of these observations, data analysis and preliminary results are presented. [less ▲]

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See detailThe WR 140 periastron passage 2009: first results from MONS and other optical sources
Fahed, R.; Moffat, A. F. J.; Zorec, J. et al

in Eversberg, Thomas; Knapen, Johan (Eds.) Stellar Winds in Interaction (2011, January 01)

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in January 2009. This object is known as the archetype of colliding wind binaries and has a ... [more ▼]

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in January 2009. This object is known as the archetype of colliding wind binaries and has a relatively large period (~ 8 years) and eccentricity (~ 0.89). We provide updated values for the orbital parameters, new estimates for the WR and O star masses and new constraints on the mass-loss rates. [less ▲]

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See detailStudy of a possible X-ray sensor based on the Plasmon Surface Resonance for the next generation of instruments
Hervé, Anthony ULg; Hastanin, Juriy ULg; Habraken, Serge ULg et al

in Bulletin de la Société Royale des Sciences de Liège (2011), 80

With the new generation of X-ray space observatories, such as IXO in preparation, we explore a new technology in order to improve the spectral resolution and the sensitivity of future instruments. We have ... [more ▼]

With the new generation of X-ray space observatories, such as IXO in preparation, we explore a new technology in order to improve the spectral resolution and the sensitivity of future instruments. We have studied the possibility to create a sensor based on the Surface Plasmon Resonance (SPR), already used in chemistry and biomedical applications, and have determined the preliminary constraints on its size, energy resolution and working temperature. [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 detailA first orbital solution for the non-thermal radio emitter Cyg OB2 #9
Nazé, Yaël ULg; Damerdji, Yassine ULg; Rauw, Grégor ULg et al

in Bulletin de la Société Royale des Sciences de Liège (2011), 80

We reported in 2008 the first detection of the binary nature of Cyg OB2 #9. Since then, we have continued our spectroscopic monitoring of this object, doubling the number of available spectra of the star ... [more ▼]

We reported in 2008 the first detection of the binary nature of Cyg OB2 #9. Since then, we have continued our spectroscopic monitoring of this object, doubling the number of available spectra of the star while covering a second periastron passage. Using a variety of techniques, the radial velocities were estimated and a first, preliminary orbital solution was derived (P=2.4 yrs). The mass ratio appears close to unity and the eccentricity is large, 0.7-0.75. [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 detailStudying massive stars with the International X-ray Observatory
Rauw, Grégor ULg; Oskinova, Lida

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

Chandra and XMM-Newton have deeply changed our view of the X-ray emission of massive stars. However, the majority of the massive stars being rather faint sources, the number of high-resolution X-ray ... [more ▼]

Chandra and XMM-Newton have deeply changed our view of the X-ray emission of massive stars. However, the majority of the massive stars being rather faint sources, the number of high-resolution X-ray spectra of massive stars remains rather limited and obtaining these spectra requires rather long exposure times. ESA, NASA and JAXA are currently designing the International X-ray Observatory (IXO) that will provide a quantum leap in collecting area compared to the current missions. In this contribution, we highlight the capabilities of IXO and its instrumentation for the study of massive stars in our Galaxy and beyond. [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 detailEffects of porosity on emergent synthetic spectra of massive stars in the X-ray domain
Hervé, Anthony ULg; Rauw, Grégor ULg

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

Massive stars possess powerful stellar winds. Studies over the last decade, including the analyses of X-ray emission-line profiles, revealed the importance of wind fragmentation and clumping and led to a ... [more ▼]

Massive stars possess powerful stellar winds. Studies over the last decade, including the analyses of X-ray emission-line profiles, revealed the importance of wind fragmentation and clumping and led to a downwards revision of the mass-loss rates. We present the first results of our code that allows to compare two models of wind fragmentation, and their consequences on the emergent X-ray spectra of massive stars. [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 detailSpectroscopic follow-up of the colliding-wind binary WR140 during the 2009 January periastron passage
Fahed, R.; Moffat, A. F. J.; Zorec, J. et al

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

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in January 2009. This object is known as the archetype of colliding wind binaries and has a ... [more ▼]

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in January 2009. This object is known as the archetype of colliding wind binaries and has a relatively large period (≃8 years) and eccentricity (≃0.9). We provide updated values for the orbital parameters, new estimates for the WR and O star masses and new constraints on the mass-loss rates. [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 detailThe multiwavelength view of hot, massive stars
Rauw, Grégor ULg; De Becker, Michaël ULg; Nazé, Yaël ULg et al

in Bulletin de la Société Royale des Sciences de Liège (2011), 80

Massive stars are certainly among the most fascinating objects of stellar populations. They trigger many astrophysical processes from star formation to the chemical enrichment of the interstellar medium ... [more ▼]

Massive stars are certainly among the most fascinating objects of stellar populations. They trigger many astrophysical processes from star formation to the chemical enrichment of the interstellar medium. Yet, their properties are still not fully understood and these objects are therefore at the core of many ongoing research activities. With the advent of new, high-performance, ground-based and space-borne facilities, the multi-wavelength investigation of hot, massive stars has definitely been boosted over the last decade. It is indeed nowadays possible to study these objects over a wide part of the electromagnetic spectrum, all the way from radio waves to gamma-rays. Motivated by this fact, we decided to organize a conference devoted to this topic in the framework of the well-established series of Liege International Astrophysical Colloquia (LIAC). The resonance in the community was extremely positive, with many proposals for high-quality contributions. During the week of 12 - 16 July 2010, 138 astrophysicists, from institutes in 21 countries all over the world, gathered in Liege to discuss how the multi-wavelength approach has revolutionized their research on massive stars. The colloquium was organized into five thematic sessions, and the present proceedings are organized along the same chapters: (1) stellar winds, diagnostics across the electromagnetic spectrum; (2) massive star formation, confronting theory and observation; (3) evolution and interaction of massive stars with their environment; (4) future instrumentation and its application to massive star research; (5) massive binaries: interaction and evolution. [less ▲]

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See detailThe Herschel view of nebulae around evolved massive stars
Vamvatira Nakou, Chloi ULg; Royer, P.; Hutsemekers, Damien ULg et al

Conference (2011)

The detailed study of the nebulae ejected from Luminous Blue Variables and the circumstellar bubbles around Wolf-Rayet stars, which radiate strongly in the IR due to the heating of dust, is crucial for ... [more ▼]

The detailed study of the nebulae ejected from Luminous Blue Variables and the circumstellar bubbles around Wolf-Rayet stars, which radiate strongly in the IR due to the heating of dust, is crucial for understanding the massive stars evolution. With Herschel, the largest telescope ever flown in space, we are able to study the gas and the dust in these circumstellar environments in the full far-infrared waveband. In the context of 'Mass-loss of Evolved StarS' Herschel guaranteed time key programme, we have obtained imaging and spectroscopic observations of nebulae associated with Luminous Blue Variable and Wolf-Rayet stars using PACS, one of the three instruments onboard Herschel. A description of these observations and first results of the data analysis are presented. [less ▲]

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See detailResults from the Herschel Key Program MESS
Groenewegen, M. A. T.; Waelkens, C.; Barlow, M. J. et al

in Kerschbaum, F.; Lebzelter, T.; Wing, R. F. (Eds.) Why Galaxies Care about AGB Stars II: Shining Examples and Common Inhabitants. ASPC 445 (2011)

MESS (Mass loss of Evolved StarS) is a Herschel Guaranteed Time Key Program that will image about 100, and do spectroscopy of about 50, post-main-sequence objects of all flavours: AGB stars, post-AGB ... [more ▼]

MESS (Mass loss of Evolved StarS) is a Herschel Guaranteed Time Key Program that will image about 100, and do spectroscopy of about 50, post-main-sequence objects of all flavours: AGB stars, post-AGB stars, planetary nebulae, luminous blue variables, Wolf-Rayet stars, and supernova remnants. In this review the implementation and current status of MESS is outlined, and first results are presented. [less ▲]

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