References of "Hutsemekers, Damien"
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See detailFormation of P Cygni Line Profiles in Relativistically Expanding Atmospheres. II. The Effect of the Continuum Frequency Shape and Limb Darkening of the Core
Hutsemekers, Damien ULg

in Astrophysical Journal (1993), 417

Abstract image available at: http://adsabs.harvard.edu/abs/1993ApJ...417...97H

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See detailGravitational lensing statistics based on a large sample of highly luminous quasars
Surdej, Jean ULg; Claeskens, Jean-François ULg; Crampton, D. et al

in Astronomical Journal (The) (1993), 105

Results on gravitational lensing statistics applied to a sample of 469 highly luminous quasars are reported. The objects were directly imaged, either from the ground under optimal seeing conditions, or ... [more ▼]

Results on gravitational lensing statistics applied to a sample of 469 highly luminous quasars are reported. The objects were directly imaged, either from the ground under optimal seeing conditions, or using the HST. We have derived values for the effectiveness parameter F of galaxies, modeled by means of singular isothermal spheres, to produce macrolensed images of distant quasars, and upper limits on the density parameter Omega(L) of compact objects with masses between 10 exp 10 and 10 exp 12 solar masses. Adopting H(0)= 50 km/s/Mpc, Omega(0)= 1, and Lambda = 0, we find that at the 99.7 percent confidence level, F is between 0.005 and 0.478 and that Omega(L) is less than 0.02. A critical discussion of these results is presented. Finally, comparing the efficiencies of ground-based and space instruments used to search for gravitational lens systems among highly luminous quasars, we conclude that for the near future, ground-based direct imaging characterized by a good dynamical range still constitutes the best observational strategy. [less ▲]

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See detailErratum - Q:1208+1011 - the Most Distant Multiply Imaged Quasar or a Binary
Magain, Pierre ULg; Surdej, Jean ULg; Vanderriest, C. et al

in Astronomy and Astrophysics (1993), 272

In the title of this Letter, the word "multiply" was accidentally omitted. The correct title is shown above.

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See detailGalaxies statistics around highly luminous quasars: the ESO Sample
van Drom, E.; Surdej, Jean ULg; Magain, Pierre ULg et al

in Surdej, Jean; Fraipont-Caro, Denise; Gosset, Eric (Eds.) et al The proceedings of the 31st Liège International Astrophysical Colloquium "Gravitational lenses in the Universe" (1993)

We present observational evidence on the correlation between the positions of Highly Luminous Quasars and those of galaxies for a sample of 136 objects, observed under good seeing conditions.

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See detailCan micro-lensing effects help to distinguish between the models for the BAL region of QSOs?
Hutsemekers, Damien ULg; Surdej, Jean ULg; van Drom, E.

in Surdej, Jean; Fraipont-Caro, D.; Gosset, Eric (Eds.) et al Liege International Astrophysical Colloquia, Gravitational Lenses in the Universe (1993)

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See detailThe relative photometric lightcurve of UM673 A&B
Daulie, G.; Hainaut, O.; Hutsemekers, Damien ULg et al

in Surdej, Jean; Fraipont-Caro, Denise; Gosset, Eric (Eds.) et al The proceedings of the 31st Liège International Astrophysical Colloquium "Gravitational lenses in (1993)

From 1987 to 1993, we have carried out at ESO a photometric monitoring of the gravitationally lensed quasar UM673. The main result is that the two lensed images of UM673 did not show any significant ... [more ▼]

From 1987 to 1993, we have carried out at ESO a photometric monitoring of the gravitationally lensed quasar UM673. The main result is that the two lensed images of UM673 did not show any significant relative variation during more than five years. [less ▲]

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See detailThe cloverleaf quasar H1413+117: a preliminary light curve
Arnould, P.; Remy, M.; Gosset, Eric ULg et al

in Surdej, Jean; Fraipont-Caro, Denise; Gosset, Eric (Eds.) et al The proceedings of the 31st Liège International Astrophysical Colloquium "Gravitational lenses in the Universe" (1993)

The cloverleaf quasar H1413+117 was discovered to be a gravitational lens system in 1988. Since then, it has been photometrically monitored essentially as part of the ESO key-program Gravitational lensing ... [more ▼]

The cloverleaf quasar H1413+117 was discovered to be a gravitational lens system in 1988. Since then, it has been photometrically monitored essentially as part of the ESO key-program Gravitational lensing: we present here a first preliminary lightcurve for its four individual images. [less ▲]

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See detailSearch for gravitational lenses in a large sample of highly luminous quasars and statistical determination of cosmological parameters
Claeskens, Jean-François ULg; Crampton, D.; Filippenko, A. V. et al

in Surdej, Jean; Fraipont-Caro, D.; Gosset, Eric (Eds.) et al The proceedings of the 31st Liège International Astrophysical Colloquium "Gravitational lenses in the Universe" (1993)

Results on gravitational lensing statistics applied to a sample of 469 highly luminous quasars are reported.

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See detailESO key programme, gravitational lensing: quasars and radio galaxies; a status report
Surdej, Jean ULg; Angonin, M. C.; Arnaud, J. et al

in Distribution of Matter in the Universe (1992, December 01)

The scientific background and objectives of our ESO Key Programme are first recalled. A brief account of our research activities (observing runs at ESO and elsewhere, meetings, etc.) is then given ... [more ▼]

The scientific background and objectives of our ESO Key Programme are first recalled. A brief account of our research activities (observing runs at ESO and elsewhere, meetings, etc.) is then given. Preliminary scientific results are presented concerning 1) our observational database for highly luminous quasars and distant powerful radiogalaxies; 2) speckle observations of highly luminous quasars; 3) the photometric monitoring and 4) detailed studies of several known gravitational lenses; 5) optical observations of 3C and 4C radio galaxies and 6) of the well known Einstein ring MG 1131+0456. [less ▲]

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See detailThe new gravitational lens candidate Q 1208+1011 and the importance of high quality data.
Magain, Pierre ULg; Surdej, Jean ULg; Vanderriest, C. et al

in The Messenger (1992), 67

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See detailQ 1208 + 1011 - The most distant imaged quasar, or a binary?
Magain, Pierre ULg; Surdej, Jean ULg; Vanderriest, C. et al

in Astronomy and Astrophysics (1992), 253(Letters), 13-16

The paper reports the discovery of a new gravitational lens candidate: the high redshift (z = 3.803) and highly luminous (V = 17.5, M[SUB]V[/SUB] = -30.3) quasar Q 1208 + 1011. As derived from the ... [more ▼]

The paper reports the discovery of a new gravitational lens candidate: the high redshift (z = 3.803) and highly luminous (V = 17.5, M[SUB]V[/SUB] = -30.3) quasar Q 1208 + 1011. As derived from the analysis of direct CCD frames taken with the ESO/MPI 2.2 m telescope, this multiple quasar consists of two pointlike images, separated by 0.45 arcsec and characterized by a brightness ratio of 3.5, in red light. Existing spectroscopic data support the gravitational lens interpretation for this system but cannot exclude the hypothesis of a binary quasar. In the former case, the spectrum suggests that, if the metallic absorption line system reported by Steidel (1990) at a redshift z = 2.9157 is associated with the deflector, the mass of the lens should be of the order of M = 7.8 x 10 exp 11 solar masses. Evaluation of a recent HST PC frame obtained for Q 1208 + 1011 within the snapshot survey for gravitational lenses confirms the above results. [less ▲]

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See detailSearch for gravitational lensing in a sample of highly luminous quasars
Magain, Pierre ULg; Hutsemekers, Damien ULg; Surdej, Jean ULg et al

in Kayser, R.; Schramm, T.; Nieser, L. (Eds.) Proceedings of the Hamburg conference on ’Gravitational Lenses’, Lecture Notes in Physics 406 (1992)

The status of the ESO survey for gravitational lensing among highly luminous quasars (HLQs) is briefly reviewed. The statistics of lensing, both concerning the multiple images and the associations of ... [more ▼]

The status of the ESO survey for gravitational lensing among highly luminous quasars (HLQs) is briefly reviewed. The statistics of lensing, both concerning the multiple images and the associations of galaxies with quasars, are examined. We find a significant overdensity of galaxies very close to the line-of-sight to the HLQs. We also report the discovery of a new multiply lensed quasar candidate. [less ▲]

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See detailGravitational lensing statistics based on a large sample of highly luminous quasars observed with ground-based telescopes and HST
Surdej, Jean ULg; Claeskens, Jean-François ULg; Crampton, D. et al

in Benvenuti, Piero; Schreier, Ethan J (Eds.) Proceedings of a ST-ECF/STScI Workshop "Science with the Hubble Space Telescope" (1992)

We present here some recent results on gravitational lensing statistics as applied to a sample of 470 highly luminous quasars.

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See detailOptical observations of gravitational lenses
Surdej, Jean ULg; Claeskens, Jean-François ULg; Hutsemekers, Damien ULg et al

in Kayser, Rainer; Schramm, Thomas; Nieser, Lars (Eds.) Proceedings of the Hamburg conference on ’Gravitational Lenses’, Lecture Notes in Physics 406 (1992)

We report here on some of the major developments achieved on optical observations of gravitational lenses since the last conference devoted to 'Gravitational Lensing'.

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See detailDeformation of P Cygni line profiles by gravitational microlensing effects
Hutsemekers, Damien ULg; Surdej, Jean ULg; Vandrom, E.

in Kayser, R.; Schramm, T.; Nieser, L. (Eds.) Gravitational Lenses, Lecture Notes in Physics, volume 406 (1992)

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See detailUnusual solar halos over La Silla
Hutsemekers, Damien ULg

in The Messenger (1991), 66

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See detailThe nature of the nebula associated with the luminous blue variable star WRA 751
Hutsemekers, Damien ULg; van Drom, E.

in Astronomy and Astrophysics (1991), 251

Narrow-band filter imagery as well as medium to high resolution spectroscopy of the nebula surrounding the luminous blue variable (LBV) star WRA 751 are presented. The nebula appears as a slowly expanding ... [more ▼]

Narrow-band filter imagery as well as medium to high resolution spectroscopy of the nebula surrounding the luminous blue variable (LBV) star WRA 751 are presented. The nebula appears as a slowly expanding H II region of low excitation characterized by a significant N/O overabundance which may be due to the presence in the nebula of nuclear processed material ejected by the star. With the recent discovery of a nebula around HR Car, all but one known galactic LBVs are now shown to be associated with a nebula. These nebula have rather similar physical characteristics, one of the most important being that all of them apparently contain processed material. [less ▲]

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See detailHR Carinae - A luminous blue variable surrounded by an arc-shaped nebula
Hutsemekers, Damien ULg; van Drom, E.

in Astronomy and Astrophysics (1991), 248

New high and medium dispersion spectroscopic observations of the luminous blue variable (LBV) star HR Car are presented, showing that this star has a multiple shell expanding atmosphere and undergoes ... [more ▼]

New high and medium dispersion spectroscopic observations of the luminous blue variable (LBV) star HR Car are presented, showing that this star has a multiple shell expanding atmosphere and undergoes spectral variations apparently correlated with the light variations similarly to the other LBVs. Most striking are the very broad emission wings (FWZI of about 3000 km/s) of the Balmer lines, reminiscent from the broad lines observed in the spectra of Of and WR stars. A kinematic distance of 5.4 kpc and a bolometric magnitude of -9.4 put HR Car among the most luminous stars of the Galaxy. The narrow band filter imagery also reveals an arc-shaped jet like nebula associated with HR Car. Spectroscopic observations of this nebula reveal an emission nature with very low excitation. Like the star itself, the nebula is characterized by a significant N/O overabundance, probably due to the presence of nuclear processed material ejected by the star. [less ▲]

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See detailA Model to Explain the Activity of Comet Levy (1990c)
Samarasinha, N. H.; A'Hearn, M. F.; Weaver, H. A. et al

in Bulletin of the American Astronomical Society (1991, June 01)

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See detailThe very massive star HDE269676 and its components
Heydari-Malayeri, M.; Hutsemekers, Damien ULg

in Astronomy and Astrophysics (1991), 244

It is shown that one of the most luminous stars of the LMC, HDE269676, is in fact a massive star cluster. On the basis of observations with the ESO New Technology Telescope (NTT) the main components of ... [more ▼]

It is shown that one of the most luminous stars of the LMC, HDE269676, is in fact a massive star cluster. On the basis of observations with the ESO New Technology Telescope (NTT) the main components of the cluster are classified and it is shown that there are several O type stars in HDE269676 instead of the one or two previously known. This is interesting for the initial mass function in the LMC and implies that the number of O type stars in the LMC is generally underestimated. The most massive star of the system being about a factor three less luminous than previously estimated is a super-giant O5f with a zero age main sequence mass of about 80 solar. [less ▲]

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