References of "Surdej, Jean"
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See detailObservations of the new gravitational lens system UM 673 = Q 0142-100
Surdej, Jean ULg; Magain, Pierre ULg; Swings, J.-P. et al

in Astronomy and Astrophysics (1988), 198

The authors have recently initiated a high resolution direct imaging survey of a selected sample of highly luminous quasars (HLQs). The observations are carried out with the 2.2 m telescope at ESO, and ... [more ▼]

The authors have recently initiated a high resolution direct imaging survey of a selected sample of highly luminous quasars (HLQs). The observations are carried out with the 2.2 m telescope at ESO, and with the VLA at the NRAO, New Mexico. Following the first observing run at ESO, the authors have reported the discovery of a new gravitational lens system for the HLQ UM 673 = Q 0142-100. Additional observations supporting this interpretation are discussed here. Application of gravitational optometry to this system is given: a value of M[SUB]0[/SUB] = 2.4×10[SUP]11[/SUP]M_sun; is derived for the mass of the lensing galaxy located between UM 673 A and B and a most likely estimate of Deltat = 7 weeks is found for the expected delay between the arrival times of a similar variability event in the two lensed images of the quasar (H[SUB]0[/SUB] = 75 km s[SUP]-1[/SUP]Mpc[SUP]-1[/SUP], q[SUB]0[/SUB] = 0). [less ▲]

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See detailSN1987a: a bright supernova in the Large Magellanic Cloud
Surdej, Jean ULg

in European Journal of Physics (1988), 9

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See detailAsteroid 45 Eugenia - Lightcurves and the pole orientation
Taylor, R. C.; Birch, P. V.; Pospieszalska-Surdej, Anna ULg et al

in ICARUS (1988), 73

Nine lightcurves of asteroid 45 Eugenia, three from 1969 and six from 1984, are given. In 1984 - 1985 the H[SUB]0[/SUB] magnitude of Eugenia, corrected to the lightcurve maximum, was 7.47 and the slope ... [more ▼]

Nine lightcurves of asteroid 45 Eugenia, three from 1969 and six from 1984, are given. In 1984 - 1985 the H[SUB]0[/SUB] magnitude of Eugenia, corrected to the lightcurve maximum, was 7.47 and the slope parameter G[SUB]0[/SUB] was 0.04. The north pole of Eugenia is within ±10° of ecliptic longitude 106° and latitude +26° (or 295° and +34°). This solution is consistent with an amplitude-aspect pole analysis. The sideral period is 0.2374645±0.0000002 day and the sense of rotation is retrograde. [less ▲]

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See detailImproved first order moment method for determination of mass-loss rates
Hutsemekers, Damien ULg; Surdej, Jean ULg

in Bianchi, L.; Gilmozzi, R. (Eds.) Mass outflows from stars and galactic nuclei; Proceedings of the Second Torino Workshop (1988)

The first order moment of P Cygni line profiles has been computed for the case of doublets and subordinate line transitions. This improved method can be used for deriving more accurate mass-loss rates of ... [more ▼]

The first order moment of P Cygni line profiles has been computed for the case of doublets and subordinate line transitions. This improved method can be used for deriving more accurate mass-loss rates of planetary nebula nuclei, broad absorption line quasars, etc. [less ▲]

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See detailAsteroid 532 Herculina - Lightcurves, pole orientation and a model
Taylor, R. C.; Birch, P. V.; Drummond, J. et al

in Icarus (1987), 69

Photoelectric lightcurves of 532 Herculina in 1984 show two maxima and two minima with a synodic rotation period of 0.39185±0.00002 day (1sigma). During some other oppositions the Herculina lightcurve has ... [more ▼]

Photoelectric lightcurves of 532 Herculina in 1984 show two maxima and two minima with a synodic rotation period of 0.39185±0.00002 day (1sigma). During some other oppositions the Herculina lightcurve has only one maximum and one minimum over that same rotation period. The absolute magnitude in V is 6.13±0.02 mag, the phase coefficient in V is 0.037±0.002, and the mean colors are B-V = +0.86±0.04 and U-B = +0.43±0.02. The authors applied photometric astrometry and the results indicate a sidereal period of 0.3918711±0.0000001 day with retrograde rotation for a north pole at 276° long and +1° lat. The uncertainty of the pole is ±1°. A model of Herculina is presented that generates lightcurves consistent with both the observed amplitudes and the timings of extrema over precisely 28,630 sidereal rotations during 30 years. [less ▲]

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See detailRevisited mass-loss rates for the nuclei of the planetary nebulae NGC 6210, NGC 6826 and NGC 6543 - The first order moment W1 of subordinate line profiles
Hutsemekers, Damien ULg; Surdej, Jean ULg

in Astronomy and Astrophysics (1987), 173

The authors present the results of numerical calculations for the first order moment W[SUB]1[/SUB] of subordinate P Cygni line profiles as a function of the parameter W[SUB]1[/SUB][SUP]0[/SUP]alphaM>n[SUB ... [more ▼]

The authors present the results of numerical calculations for the first order moment W[SUB]1[/SUB] of subordinate P Cygni line profiles as a function of the parameter W[SUB]1[/SUB][SUP]0[/SUP]alphaM>n[SUB]g[/SUB]<[SUB]s[/SUB], where Mrepresents the mass-loss rate of the central star and >n[SUB]g[/SUB]<[SUB]s[/SUB] the average fractional abundance of the relevant ion across the region of the envelope where the subordinate line profile is formed. The calculations clearly show that for unsaturated P Cygni line profiles the relation W[SUB]1[/SUB]alphaM>n[SUB]g[/SUB]<[SUB]s[/SUB] holds irrespective of the type of the opacity and/or velocity distributions. For currently observed P Cygni line profiles, the misuse of this relation can lead to an underestimate of the mass-loss rates by more than one order of magnitude. This is illustrated for the case of 3 selected central stars of planetary nebulae (NGC 6210, NGC 6826 and NGC 6543) for which mass-loss rates have been revisited. [less ▲]

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See detailIs There an Alignment of Quasars Near NGC 520?
Gosset, Eric ULg; Surdej, Jean ULg; Swings, Jean-Pierre ULg

in Hewitt, Adelaide; Burbidge, Geoffrey; Fang, Li Zhi (Eds.) IAU Symposium, No. 124 "Observational Cosmology" (1987)

Three statistical tests applied to 65 UV excess objects in the field of NGC 520 lead to no detection of any significant alignment.

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See detailSupernova 1987a in the Large Magellanic Cloud: an observational overview
Surdej, Jean ULg

Article for general public (1987)

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See detailDernière nouvelle: SN1987a brille toujours dans le Grand Nuage de Magellan
Surdej, Jean ULg

Article for general public (1987)

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See detailL'explosion d'une supernova dans le Grand Nuage de Magellan
Surdej, Jean ULg

Article for general public (1987)

The author presents here an overview of the main results obtained so far about the bright supernova SN 1987A which exploded in the Large Magellanic Cloud.

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See detailGeometry of the mass-outflows around broad absorption line QSOs and formation of the complex Ly-alpha + N V line profile
Surdej, Jean ULg; Hutsemekers, Damien ULg

in Astronomy and Astrophysics (1987), 177

The possibility that the observed broad absorption line (BAL) profiles are formed in spherically symmetric atmospheres is investigated, and it is found that BAL and non-BAL QSOs form two distinct classes ... [more ▼]

The possibility that the observed broad absorption line (BAL) profiles are formed in spherically symmetric atmospheres is investigated, and it is found that BAL and non-BAL QSOs form two distinct classes of quasars. It is shown that the small residual intensity and large equivalent width noted for some absorption troughs may be reproduced by the resonance scattering of line photons across spherically symmetric BAL regions. N V emission strength is found to be higher in the spectrum of BAL QSOs than in that of non-BAL QSOs. Good agreement between theory and the observed attenuation of the Ly-alpha emission line, the observed enhancement of the N V emission strength, and the possible presence of a shoulderlike feature in the red wing of the N V emission profile is obtained. [less ▲]

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See detailA new case of gravitational lensing
Surdej, Jean ULg; Magain, Pierre ULg; Swings, J.-P. et al

in Nature (1987), 329

The authors have begun a systematic search from ESO for gravitational lens systems in a selected sample of highly luminous quasars; M[SUB]V[/SUB] < -29.0. They give a brief description of their first ... [more ▼]

The authors have begun a systematic search from ESO for gravitational lens systems in a selected sample of highly luminous quasars; M[SUB]V[/SUB] < -29.0. They give a brief description of their first identified gravitational lens system UM673 = Q0142-100 = PHL3703. It consists of two images, A (m[SUB]R[/SUB] = 16.9) and B (m[SUB]R[/SUB] = 19.1), separated by 2.2 arc s at a redshift z[SUB]q[/SUB] = 2.719. The lensing galaxy (m[SUB]R[/SUB] â 19, Z[SUB]L[/SUB] â 0.49) has also been found. It lies very near the line connecting the two QSO images, â ¡0.8 arc s from the fainter one. A value M[SUB]0[/SUB] â 2.4×10[SUP]11[/SUP]M_sun; for the mass of the lensing galaxy and Deltat â 7 weeks for most likely travel-time difference between the two light paths to the QSO are found (assuming H[SUB]0[/SUB] = 75 km s[SUP]-1[/SUP]Mpc[SUP]-1[/SUP], q[SUB]0[/SUB] = 0). [less ▲]

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See detailL'objet le plus éloigné dans notre univers: Q0046-293
Surdej, Jean ULg

in Ciel et Terre (1987), 103

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See detailThe high redshift of quasars
Surdej, Jean ULg

in Kleczek, J. (Ed.) Exercises in astronomy.. 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. Palous, 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 detailMirages caused by a gravitational lens
Surdej, Jean ULg

in Kleczek, J. (Ed.) Exercises in astronomy...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. Palous, 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 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 detailOPTOPUS observations of Halley’s comet
Lund, G.; Surdej, Jean ULg

in The Messenger (1986), 43

The multiobject spectrograph OPTOPUS, for use at the 3.6-m ESO telescope with the CCD detector, is described, and preliminary results of spectra obtained in December 1985 of selected regions in the coma ... [more ▼]

The multiobject spectrograph OPTOPUS, for use at the 3.6-m ESO telescope with the CCD detector, is described, and preliminary results of spectra obtained in December 1985 of selected regions in the coma of Halley's comet are presented. The instrument's 54 separately cabled optical fibers, whose input ends are located in the focal plane by connectors plugged into drilled starplates, enable light to be guided from freely distributed points in a 33 arcmin zone of the Cassegrain focal plane, to a common slit. The spectra show the presence of a very faint continuum, due to the scattering of solar line photons in the inner region of the coma, on which is superimposed the bright emission bands of molecules such as CN, C2, C3, and NH2. The spectra also indicate that the brightness decrease of molecular bands as a function of the projected radial distance is not the same for different molecules. 3-3 (PDF) ESO [less ▲]

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See detailSpectroscopy of the QSSOs Q0118-031 A, B, C
Robertson, J. G.; Shaver, P. A.; Surdej, Jean ULg et al

in Monthly Notices of the Royal Astronomical Society (1986), 219

Optical spectroscopy of the three quasars Q0118-031A, B, C is presented. These objects which have emission redshifts of 12.445, 2.112 and 1.165 respectively, form a triplet on the plane of the sky with ... [more ▼]

Optical spectroscopy of the three quasars Q0118-031A, B, C is presented. These objects which have emission redshifts of 12.445, 2.112 and 1.165 respectively, form a triplet on the plane of the sky with separations of 4.8, 4.9 and 0.4 arcmins. Low dispersion spectra were obtained for all three objects, and intermediate dispersion spectra instrumental in the search for absorption lines were obtained for objects B and C. QSO B was found to have a rich absorption line spectrum, with definite systems at z(abs) 1.4648 and 2.0192. No absorption lines were found in the given spectrum for QSO C. Estimated column densities and velocity dispersions are given for the absorption systems in QSO B, and it is noted that the one at z(abs) = 1.4648 differs by only 2400 + or - 250 km/s from the emission redshift of QSO A. Since the spatial separation was predicted to be 1.2 Mpc, this absorption system may be due to material related to a galaxy in a cluster which also contains QSO A. It is suggested that this associated absorption is connected to the fact that quasars are located in regions of higher than average matter density. [less ▲]

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See detailUltraviolet Excess Quasar Candidates in Large Fields: a Status Report Concerning the NGC 450 Area
Gosset, Eric ULg; Surdej, Jean ULg; Swings, Jean-Pierre ULg

in Swarup, G.; Kapahi, V. K. (Eds.) Quasars (1986)

New results are presented based on several statistical analyses of a 25 square degree field around NGC 450. They include the detection of a clustering on a small scale (≅10 arcminutes) and possible large ... [more ▼]

New results are presented based on several statistical analyses of a 25 square degree field around NGC 450. They include the detection of a clustering on a small scale (≅10 arcminutes) and possible large scale inhomogeneities. [less ▲]

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See detailDetermination of mass-loss rates of planetary nebulae nuclei using the first order moment of P Cygni line profiles.
Hutsemekers, Damien ULg; Surdej, Jean ULg

in Comptes rendus sur les Journées de Strasbourg, 8ème réunion - Les Nébuleuses Planétaires (1986)

The authors conclude that the mass-loss rates of planetary nebulae nuclei derived by Cerruti-Sola, Perinotto (1985) have been systematically underestimated by one or nearly two orders of magnitude.

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