Publications of Jean-Marie Vreux
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See detailWR22 as a core hydrogen-burning Wolf-Rayet star
Rauw, Grégor ULiege; Vreux, Jean-Marie ULiege; Gosset, Eric ULiege et al

in Stellar evolution: what should be done; 32nd Liege International Astrophysical Coll. (1995)

The analysis of an extensive sample of high resolution spectra of the Wolf-Rayet binary WR22 recently allowed us to determine a minimum mass of 72 M_solar for the WN7 star. With such a high mass, WR22 is ... [more ▼]

The analysis of an extensive sample of high resolution spectra of the Wolf-Rayet binary WR22 recently allowed us to determine a minimum mass of 72 M_solar for the WN7 star. With such a high mass, WR22 is expected to be a core H-Burning star which has just evolved from a progenitor of at least 90-110 M_solar. [less ▲]

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See detailA seven year campaign on WR 22
Rauw, Grégor ULiege; Vreux, Jean-Marie ULiege; Gosset, Eric ULiege et al

in Wolf-Rayet Stars: Binaries; Colliding Winds; Evolution. International Astronomical Union. Symposium no. 163 (1995)

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See detailFurther results on the line-profile variability of WR 134
Gosset, Eric ULiege; Vreux, Jean-Marie ULiege; Andrillat, Y.

in Astrophysics & Space Science (1994, November 01), 221

We discuss a few conclusions previously derived from the analysis of the line-profile variability of the Wolf-Rayet star WR 134, some details are made more explicit. In addition, we present a new set of ... [more ▼]

We discuss a few conclusions previously derived from the analysis of the line-profile variability of the Wolf-Rayet star WR 134, some details are made more explicit. In addition, we present a new set of data and briefly comment on recent results deduced from its analysis. [less ▲]

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See detailEtude de la variabilité des étoiles de type Wolf-Rayet
Gosset, Eric ULiege; Vreux, Jean-Marie ULiege

Book published by Académie royale de Belgique - Académie royale de Belgique (1994)

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See detailPhotometric monitoring of Wolf-Rayet stars: Strömgren uvby and narrow-band photometry
Gosset, Eric ULiege; Rauw, Grégor ULiege; Manfroid, Jean ULiege et al

in NATO ASIC Proc. 436: The Impact of Long-Term Monitoring on Variable Star Research: Astrophysics (1994)

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See detailWR 134 line-profile variability revisited
Vreux, Jean-Marie ULiege; Gosset, Eric ULiege; Bohannan, B. et al

in Astronomy and Astrophysics (1992), 256

Line profile variations of WR 134 are analyzed on more than 200 spectra collected at Haute Provence Observatory and at Kitt Peak National Observatory. No conclusive evidence is found for a periodic ... [more ▼]

Line profile variations of WR 134 are analyzed on more than 200 spectra collected at Haute Provence Observatory and at Kitt Peak National Observatory. No conclusive evidence is found for a periodic behavior. However, for some frequencies, for example, the ones close to nu = (n x 0.5)/d, the data are ill-distributed, and the existence of a related periodic phenomenon cannot be completely ruled out. This does not mean that the variability presents a purely random behavior. Several new characteristics of the observed deformations are extracted from the analysis of the spectra and it is tentatively suggested that these could be the signature of a bipolar flow. [less ▲]

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See detailWR 22 is an Eclipsing Binary Star
Gosset, Eric ULiege; Remy, Marc; Manfroid, Jean ULiege et al

in Information Bulletin on Variable Stars (1991), 3571

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See detailAnalysis of the light variations of the Wolf-Rayet star WR16
Gosset, Eric ULiege; Vreux, Jean-Marie ULiege; Manfroid, Jean ULiege et al

in Astronomy and Astrophysics. Supplement Series (1990), 84

This paper presents new data sets of Stromgren differential photometry observations of the Wolf-Rayet star WR16, collected at the ESO (La Silla, Chile). Results of detailed data analyses support previous ... [more ▼]

This paper presents new data sets of Stromgren differential photometry observations of the Wolf-Rayet star WR16, collected at the ESO (La Silla, Chile). Results of detailed data analyses support previous findings concerning the variability of WR16, with dominating power at frequencies below 1.5/d. The variations were found to be positively correlated on time lags up to about two days, a characteristic delay larger than the time of replacement of a typical WR star wind. A simple stochastic model is developed for the low frequency variability of the star, which is able to explain the available observations. [less ▲]

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See detailThe possible biperiodicity of WR 40
Gosset, Eric ULiege; Vreux, Jean-Marie ULiege

in Astronomy and Astrophysics (1990), 231

Strong arguments are presented in favor of the simultaneous presence of two periodicities in the variability of the Wolf-Rayet star WR 40. The frequencies are nu(A) = 0.16/d and nu(B) = 0.40/d. Some ... [more ▼]

Strong arguments are presented in favor of the simultaneous presence of two periodicities in the variability of the Wolf-Rayet star WR 40. The frequencies are nu(A) = 0.16/d and nu(B) = 0.40/d. Some uncertainties remain concerning the choice of the actual one-year alias. On the basis of a detailed statistical analysis, reliable evidence that the variability related to nu(B) could be coherent is also presented: this points out nu(B) as a possible fundamental frequency linked to the 'core' of WR 40. No firm conclusion could be drawn about nu(A), suggesting that it could be a recurrent quasi-periodicity or a second order periodicity (e.g., a beat frequency). The two frequencies are sometimes hidden by the white noise, or slightly correlated, random process that constitutes the third component of the variability of WR 40. [less ▲]

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See detailAnalysis of the photometric variability of WR40
Gosset, Eric ULiege; Vreux, Jean-Marie ULiege; Manfroid, Jean ULiege et al

in Monthly Notices of the Royal Astronomical Society (1989), 238

New photometric data on the star WR40 are presented and, together with data already published, are analyzed in a detailed and homogeneous manner in order to investigate the variability of the star. Good ... [more ▼]

New photometric data on the star WR40 are presented and, together with data already published, are analyzed in a detailed and homogeneous manner in order to investigate the variability of the star. Good evidence is presented for the existence of a periodicity P = 6.250 + or - 0.078 day with a semiamplitude of 0.010 mag in the Stromgren b filter. Only part of the 0.1 mag peak-to-peak variation of the star can be explained in this way and other interesting features of the variability are outlined. The physical origin of the periodicity is discussed. [less ▲]

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See detailNew results on the variability of some WN stars
Gosset, Eric ULiege; Vreux, Jean-Marie ULiege; Manfroid, Jean ULiege et al

in Davidson, K.; Moffat, A. F. J.; Lamers, H.J.G.L.M. (Eds.) Physics of Luminous Blue Variables (1989)

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See detailWhich photometric period for WR 16?
Manfroid, Jean ULiege; Gosset, Eric ULiege; Vreux, Jean-Marie ULiege

in Astronomy and Astrophysics (1987), 185

Analysis of new and already published photometric observations shows that the Wolf-Rayet star WR 16 = HD 86161 is not a binary system (WR + compact, P = 5.365 d) as claimed by Moffat and Niemela (1982 ... [more ▼]

Analysis of new and already published photometric observations shows that the Wolf-Rayet star WR 16 = HD 86161 is not a binary system (WR + compact, P = 5.365 d) as claimed by Moffat and Niemela (1982). Instead it is shown that the simultaneous presence of two periodicities (about 1.3 and 2.5 days) is necessary to account for the observed variations during at least one observing run. The variability of the B9p star HD 86199, previously used as a comparison for a photometric study of WR 16, is established. [less ▲]

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See detailHD 151932 variability revisited
Vreux, Jean-Marie ULiege; Manfroid, Jean ULiege; Scuflaire, Richard ULiege et al

in Astronomy and Astrophysics (1987), 180

The observation of variations in the blue absorption component of the He I lines as well as in the Si IV 4089 emission line of HD 151932 is reported. Possible explanations for these variations are ... [more ▼]

The observation of variations in the blue absorption component of the He I lines as well as in the Si IV 4089 emission line of HD 151932 is reported. Possible explanations for these variations are addressed, and it is concluded that none is satisfactory. The possibility of a periodicity in the variations is briefly considered. [less ▲]

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See detailThe possible appearance of a second period in the WN 5 star EZ Canis Majoris
Gosset, Eric ULiege; Vreux, Jean-Marie ULiege

in Astronomy and Astrophysics (1987), 178

Previously published photometric data on EZ Canis Majoris are reanalyzed. It is shown by different techniques that a sine-wave type periodicity close to one third of the claimed period of P = 3[SUP]d[/SUP ... [more ▼]

Previously published photometric data on EZ Canis Majoris are reanalyzed. It is shown by different techniques that a sine-wave type periodicity close to one third of the claimed period of P = 3[SUP]d[/SUP].766 may also be present in what was considered as peculiarities in the lightcurve. The data available do not allow to known if this second period is precisely equal or only close to one third of P nor if there is some dependence between the two. In any case, the mere possible existence of such a second period is an interesting fact in the discussion concerning the possible existence of non-radial pulsations in some WR stars. [less ▲]

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See detailPhotometric Observations of WR78 = HD 151932
Magain, Pierre ULiege; Vreux, Jean-Marie ULiege; Manfroid, Jean ULiege

in Information Bulletin on Variable Stars (1987), 3022

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See detailExercises in astronomy.
Kleczek, J.; Minnaert, M. G. J.; Allen, D. A. et al

in Exercises in astronomy.. J. Kleczek (Editor).Revised and extended edition of "Practical work in elementary astronomy" by M. G. J. Minnaert. D. ReidelPublishing Co., Dordrecht, The Netherlands. 24+339 pp. Price Dfl. 140.00, US 64.00, £ 49.50 cloth; Dfl. 59.00, US 19.50, £ 18.00 paper (1987). ISBN 90-277-2409-1 cloth, ISBN 90-277-2423-7 paper. (1987)

This book is an updated and considerably extended version of Minnaert's work published in 1969 (01.003.051).Many new exercises referring to new observational techniques and methods have been incorporated ... [more ▼]

This book is an updated and considerably extended version of Minnaert's work published in 1969 (01.003.051).Many new exercises referring to new observational techniques and methods have been incorporated by the editor in collaboration with the contributing authors D. A. Allen, Z. Ceplechka, S. Ferraz Mello, K. J. Gordon, L. Houziaux, C. Jaschek, Z. Kopal, J. Manfroid, J. PalouÅ¡, J. Podolský, G. R. Quast, J. Surdej, A. B. Underhill, J. M. Vreux, D. G. Wentzel.The exercises are organized in the following sections:A. The planetary system: 1. Space and time, instruments. 2. The motions of celestial bodies. 3. Planets and satellites.B. The stars: 1. The Sun. 2. Stars and nebulae. 3. Stellar systems. [less ▲]

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See detailPhotometry of the G8V Star HD 192020
Vreux, Jean-Marie ULiege; Manfroid, Jean ULiege

in Information Bulletin on Variable Stars (1985), 2822

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See detailPhotometry of the Wolf-Rayet Star HD 191765
Vreux, Jean-Marie ULiege; Manfroid, Jean ULiege

in Information Bulletin on Variable Stars (1985), 2821

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See detailHD 192163 variability revisited - A very short period WR binary or a pulsating star?
Vreux, Jean-Marie ULiege; Andrillat, Y.; Gosset, Eric ULiege

in Astronomy and Astrophysics (1985), 149

The present reexamination of emission line variations in HD 192163 on the basis of 23 spectra takes into account stratification effects in the atmosphere of the WR stars, as well as the necessity for a ... [more ▼]

The present reexamination of emission line variations in HD 192163 on the basis of 23 spectra takes into account stratification effects in the atmosphere of the WR stars, as well as the necessity for a high N/R ratio. Because of the peculiar shape of the profiles, the wavelength shifts are measured by comparing the position of every observation to a nearly noise-free profile that is taken as reference. The most probable period supported by the present data is either 0.45 or 0.31 days; these two periods are one-day aliases of each other. [less ▲]

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See detailObservations photographiques de la comète Kohoutek (1973 f) au grand télescope de Schmidt franco-liégeois
Dossin, P.; Heck, A.; Klutz, M. et al

in Ciel et Terre (1974), 90

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