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See detailTrente années d'Astronomie et de Physique Atomique à l'Université de Mons-Hainaut (1968-1998)
Biémont, Emile ULg; Houziaux, Léo ULg

Book published by Public. de l'Université de Mons-Hainaut (1999)

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See detailNebulae around R Coronae Borealis stars - Clues to their evolutionary status?
Pollacco, D. L.; Hill, P. W.; Houziaux, Léo ULg et al

in Monthly Notices of the Royal Astronomical Society (1991), 248

Imaging and spectroscopy are presented of the classical R CrB star UW Cen obtained when the star was in a deep minimum. These show the presence of a faint reflection nebula, the inner parts of which ... [more ▼]

Imaging and spectroscopy are presented of the classical R CrB star UW Cen obtained when the star was in a deep minimum. These show the presence of a faint reflection nebula, the inner parts of which display two sets of symmetrical 'jets' centered on the star. The possibilities of whether the nebular structure can be associated with last thermal pulse evolution, white dwarf merger, or the mechanism causing the characteristic R CrB minima are discussed. [less ▲]

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See detailThe May-July 1989 Crisis of V348 Sgr
Manfroid, Jean ULg; Houziaux, Léo ULg

in Information Bulletin on Variable Stars (1989), 3375

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See detailHot carbon stars - More about V348 SGR
Houziaux, Léo ULg; Bouchet, P.; Heck, A. et al

in Quarterly Journal of the Royal Astronomical Society (1987), 28

New observational techniques (sensitive receivers, access to ultraviolet and infrared spectroscopy), as well as recent theoretical investigations on advanced stages of stellar evolution focus attention ... [more ▼]

New observational techniques (sensitive receivers, access to ultraviolet and infrared spectroscopy), as well as recent theoretical investigations on advanced stages of stellar evolution focus attention again on hydrogen-poor and helium-rich objects known as "carbon stars". The case of the hot peculiar variable V348 Sgr is discussed. New visible and infrared observations are presented, but the exact nature of the star remains much of an enigma. [less ▲]

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See detailSpectral energy distribution and interstellar reddening
Houziaux, Léo ULg; Manfroid, Jean ULg

in IAU Colloq. 92: Physics of Be Stars (1987)

Recent results on flux distribution of Be stars from 320 to 850nm are reviewed. It appears that data are available for only 10 to 15 percent of the objects recognized as 'normal' Be stars. The main ... [more ▼]

Recent results on flux distribution of Be stars from 320 to 850nm are reviewed. It appears that data are available for only 10 to 15 percent of the objects recognized as 'normal' Be stars. The main current problems appear to be the variability of the continuous radiation, and the correction for interstellar reddening. Various attempts to solve these matters are discussed. The need for fairly high (1nm) resolution spectral scans obtained simultaneously with data in other spectral ranges, repeated at appropriate intervals of time, is stressed. Such requirements make it necessary to restrict the observing programmes to a limited sample of carefully chosen objects. [less ▲]

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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 detailPhotometric variations of the irregular variable V348 SGR
Heck, A.; Houziaux, Léo ULg; Manfroid, Jean ULg et al

in Astronomy and Astrophysics. Supplement Series (1985), 61

The authors report visual estimates and photometric observations in various wavelength ranges of the irregular variable V348 Sgr. They cover dramatic drops of brightness (from V â 12.5 to â 18) which ... [more ▼]

The authors report visual estimates and photometric observations in various wavelength ranges of the irregular variable V348 Sgr. They cover dramatic drops of brightness (from V â 12.5 to â 18) which occurred in 1972, 1973 and 1981 with a time scale much shorter than the characteristic time mentioned by previous observers. These deep minima are, to our knowledge, the best followed up to now. The maximum brightness of the object seems also to correspond to V â 12 and not 10.5 as reported earlier. The minima reach V â 18, but this might represent the nebular contribution while the star itself might even go fainter. The main conclusions of this compilation are probably that the characteristic times given by Herbig (1958) from appearances on Harvard plates are most likely incorrect and that it is impossible to give one at all. The field of V348 Sgr has also been observed in the uvby system and a sequence is provided in this paper. [less ▲]

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See detailAn estimate of V348 SGR effective temperature
Heber, U.; Heck, A.; Houziaux, Léo ULg et al

in Fourth European IUE Conference (1984, July 01)

The IUE low dispersion spectra of the irregular variable V348 Sgr taken close to maximum light were compared with those of the B-type stars HD 53138 and HD 58350 and with those of the extreme helium stars ... [more ▼]

The IUE low dispersion spectra of the irregular variable V348 Sgr taken close to maximum light were compared with those of the B-type stars HD 53138 and HD 58350 and with those of the extreme helium stars HD 12448 and LS II + 33 deg 005. Energy distribution of V348 Sgr was compared with a theoretical continuous distribution based on UBVRI and uvby photometric measurements close to maximum brightness. Results show that V348 Sgr has a carbon-rich atmosphere and a spectral type between s+B3 and s+B5 in the UV (corresponding to between B3 Ia and B5 Ia in the visible). The object probably belongs to the group of extreme helium stars with an effective temperature of 15,000 to 16,000 K. [less ▲]

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See detailAugust 1981 Crisis of V348 Sgr
Heck, A.; Houziaux, Léo ULg; Manfroid, Jean ULg

in Information Bulletin on Variable Stars (1982), 2184

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See detailObservations of southern nebulae
Danks, A. C.; Houziaux, Léo ULg; Manfroid, Jean ULg

in Astrophysics & Space Science (1976), 39

Spectroscopic observations of 10 H II regions in the southern hemisphere are presented. The observations cover the spectral region 3600-8000 A.

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