References of "Surdej, Jean"
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See detailProfiles of a Key Programme: Gravitational Lensing
Surdej, Jean ULg; Arnaud, J.; Borgeest, U. et al

in The Messenger (1989), 55

Prior to Professor van der Laan's enquiry, in the March 1988 issue of the Messenger, on the general interest among astronomers from the European community to possibly participate in Key Programmes (KPs ... [more ▼]

Prior to Professor van der Laan's enquiry, in the March 1988 issue of the Messenger, on the general interest among astronomers from the European community to possibly participate in Key Programmes (KPs) at the European 80uthern Observatory, at least three distinct groups (including more than half of the above authors) were already involved in the study of "gravitational lensing" effects (see box on pages 10-11). Observations were being performed with the help of various telescopes on La 8illa as weil as at other observatories (VLA, CFHT, Palomar, Kitt Peak, etc.). [less ▲]

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See detailRevisited Mass-Loss Rates of Planetary Nebula Nuclei Observed with IUE
Hutsemekers, Damien ULg; Surdej, Jean ULg

in Torres-Peimbert, Silvia (Ed.) Planetary Nebulae, 131st. Symposium of the International Astronomical Union (1989)

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See detailDiscovery of a quadruply lensed quasar - The 'clover leaf' H1413 + 117
Magain, Pierre ULg; Surdej, Jean ULg; Swings, J.-P. et al

in Nature (1988), 334

The authors report the discovery of a second gravitational lens system in the broad absorption line quasar H1413+117. Four images of comparable brightness are seen, separated by â ¡1 arcsec. The unique ... [more ▼]

The authors report the discovery of a second gravitational lens system in the broad absorption line quasar H1413+117. Four images of comparable brightness are seen, separated by â ¡1 arcsec. The unique configuration of the images, together with the fairly rare occurrence of this type of quasar, makes it incontrovertible that this is a lensed system, not a cluster of quasars. (See also 159.062). [less ▲]

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See detailStatistical tests applied to the spatial distribution of quasars in several fields.
Gosset, Eric ULg; Surdej, Jean ULg; Swings, Jean-Pierre ULg

in Osmer, P. S.; Porter, A. C.; Green, R. F. (Eds.) et al Optical surveys for quasars (1988)

The authors discuss the application of different statistical tests to the study of the spatial distribution of quasars. Applications to data sets of optically selected quasars lead to the detection of a ... [more ▼]

The authors discuss the application of different statistical tests to the study of the spatial distribution of quasars. Applications to data sets of optically selected quasars lead to the detection of a clustering at a typical scale of 10 arcmin. Furthermore, the spatial distribution of quasars in a field around NGC 450 shows a deviation from randomness, towards clustering, at a scale of 10 h[SUP]-1[/SUP]Mpc. [less ▲]

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See detailSurveys of Ultraviolet Excess Quasar Candidates in Three Large Fields
Swings, Jean-Pierre ULg; Surdej, Jean ULg; Gosset, Eric ULg

in Osmer, Patric S. (Ed.) Astron. Soc. of the Pac. Conf. Series: Optical Surveys for Quasars (1988)

A general description is given of the surveys performed in the fields around NGC 450 and NGC 520, and in the ESO field No. 300 with the aim of detecting ultraviolet excess quasar candidates.

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See detailSN1987a: une supernova très brillante dans le Grand Nuage de Magellan
Némry, F.; Surdej, Jean ULg

Article for general public (1988)

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See detailNew arguments supporting the intrinsic origin of BAL QSOs - Formation of the complex Ly-alpha+NV line profile
Hutsemekers, Damien ULg; Surdej, Jean ULg

in Bianchi, L.; Gilmozzi, R. (Eds.) Proceedings of the Second Torino Workshop "Mass Outflows from Stars and Galactic Nuclei" (1988)

A study is presented to further elucidate the question of whether or not all quasars are affected by the BAL phenomenon. The possibility that observed BAL profiles are formed in spherically symmetric ... [more ▼]

A study is presented to further elucidate the question of whether or not all quasars are affected by the BAL phenomenon. The possibility that observed BAL profiles are formed in spherically symmetric expanding atmospheres is investigated. [less ▲]

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See detailPreliminary results from a search for gravitational lensing within a sample of highly luminous quasars
Surdej, Jean ULg; Magain, Pierre ULg; Swings, Jean-Pierre ULg et al

in Balkowski, C.; Gordon, S. (Eds.) Proceedings to the First D.A.E.C. workshop on "Large Scale Structures" (1988)

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See detailSearch for Gravitational Lensing from a Survey of Highly Luminous Quasars
Surdej, Jean ULg; Swings, J.-P.; Magain, Pierre ULg et al

in Osmer, Patrick; Phillips, M. M. (Eds.) ASP Conference Series, Volume 2, Proceedings of a Workshop on Optical Surveys for Quasars (1988)

The authors have shown that their search for gravitational lensing from a survey of optically selected highly luminous quasars (HLQ) appears very promising. Observational features (multiple images, image ... [more ▼]

The authors have shown that their search for gravitational lensing from a survey of optically selected highly luminous quasars (HLQ) appears very promising. Observational features (multiple images, image elongation, jet-like feature, fuzz, etc.) possibly associated with the HLQ phenomenon have been detected for more than 20% of the objects under study. While it is not yet known how many of the HLQs are gravitational mirages, at least 5 (out of 111) of the investigated quasars appear to be highly luminous because of amplification of their brightness by gravitational lensing. [less ▲]

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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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