References of "Hutsemekers, Damien"
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See detailMulti-wavelength study of the gravitational lens system RXS J1131-1231 - III. Long slit spectroscopy: micro-lensing probes the QSO structure
Sluse, Dominique ULg; Claeskens, Jean-François ULg; Hutsemekers, Damien ULg et al

in Astronomy and Astrophysics (2007), 468(3), 885-901

Aims. We discuss and characterize micro-lensing among the 3 brightest lensed images (A-B-C) of the gravitational lens system RXS J1131-1231 (a quadruply imaged AGN) by means of long slit optical and NIR ... [more ▼]

Aims. We discuss and characterize micro-lensing among the 3 brightest lensed images (A-B-C) of the gravitational lens system RXS J1131-1231 (a quadruply imaged AGN) by means of long slit optical and NIR spectroscopy. Qualitative constraints on the size of different emission regions are derived. We also perform a spectroscopic study of two field galaxies located within 1.6 arcmin radius from the lens. Methods. We decompose the spectra into their individual emission components using a multi-component fitting approach. A complementary decomposition of the spectra enables us to isolate the macro-lensed fraction of the spectra independently of any spectral modelling. Results. 1. The data support micro-lensing de-amplification of images A and C. Not only is the continuum emission microlensed in those images but also a fraction of the Broad Line emitting Region (BLR). 2. Micro-lensing of a very broad component of Mg II emission line suggests that the corresponding emission occurs in a region more compact than the other components of the emission line. 3. We find evidence that a large fraction of the Fe II emission arises in the outer parts of the BLR. We also find a very compact emitting region in the ranges 3080-3540 angstrom and 4630-4800 angstrom that is likely associated with Fe II. 4. The [O III] narrow emission line regions are partly spatially resolved. This enables us to put a lower limit of similar to 110h(-1) pc on their intrinsic size. 5. Analysis of Mg II absorption found in the spectra indicates that the absorbing medium is intrinsic to the quasar, has a covering factor of 20%, and is constituted of small clouds homogeneously distributed in front of the continuum and BLRs. 6. Two neighbour galaxies are detected at redshifts z = 0.10 and z = 0.289. These galaxies are possible members of galaxy groups reported at those redshifts. [less ▲]

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See detailNuclear spin temperature of ammonia in Comet 9P/Tempel 1 before and after the Deep Impact event
Kawakita, Hideyo; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Icarus (2007), 187

The Deep Impact mission succeeded in excavating inner materials from the nucleus of Comet 9P/Tempel 1 on 2005 July 04 (at 05:52 UT). Comet 9P/Tempel 1 is one of Jupiter family short period comets, which ... [more ▼]

The Deep Impact mission succeeded in excavating inner materials from the nucleus of Comet 9P/Tempel 1 on 2005 July 04 (at 05:52 UT). Comet 9P/Tempel 1 is one of Jupiter family short period comets, which might originate in the Kuiper belt region in the solar nebula. In order to characterize the comet and to support the mission from the ground-based observatory, optical high-dispersion spectroscopic observations were carried out with the echelle spectrograph (UVES) mounted on the 8-m telescope VLT (UT2) before and after the Deep Impact event. Ortho-to-para abundance ratios (OPRs) of cometary ammonia were determined from the NH[SUB]2[/SUB] emission spectra. The OPRs of ammonia on July 3.996 UT and 4.997 UT were derived to be 1.28±0.07 (nuclear spin temperature: T[SUB][/SUB]=24±2 K) and 1.26±0.08 (T[SUB][/SUB]=25±2 K), respectively. There is no significant change between before and after the impact. Actually, most materials ejected from the impact site could have moved away from the nucleus on July 4.997 UT, about 17 h after the impact. However, a small fraction of the ejected materials might remain in the slit of UVES instrument at that time because an excess of about 20% in the NH[SUB]2[/SUB] emission flux is observed above the normal activity level was found [Manfroid, J., Hutsemékers, D., Jehin, E., Cochran, A.L., Arpigny, C., Jackson, W.M., Meech, K.J., Schulz, R., Zucconi, J.-M., 2007. Icarus. This issue]. If the excess of NH[SUB]2[/SUB] on July 04.997 UT was produced from icy materials excavated by the Deep Impact, then an upper-limit of the ammonia OPR would be 1.75 (T[SUB][/SUB]>17 K) for those materials. On the other hand, the OPR of ammonia produced from the quiescent sources was similar to that of the Oort cloud comets observed so far. This fact may imply that physical conditions where cometary ices formed were similar between Comet 9P/Tempel 1 and the Oort cloud comets. [less ▲]

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See detailThe impact and rotational light curves of Comet 9P/Tempel 1
Manfroid, Jean ULg; Hutsemekers, Damien ULg; Jehin, Emmanuel ULg et al

in Icarus: International Journal of Solar System Studies (2007), 187

UVES and HIRES high-resolution spectra of Comet 9P/Tempel 1 are used to investigate the impact and rotational light curves of various species with a view toward building a simple model of the distribution ... [more ▼]

UVES and HIRES high-resolution spectra of Comet 9P/Tempel 1 are used to investigate the impact and rotational light curves of various species with a view toward building a simple model of the distribution and activity of the sources. The emission by OH, NH, CN, C[SUB]3[/SUB], CH, C[SUB]2[/SUB], NH[SUB]2[/SUB], and OI, are analyzed, as well as the light scattered by the dust. It is found that a simple model reproduces fairly well the impact light curves of all species combining the production of the observed molecules and the expansion of the material throughout the slit. The impact light curves are consistent with velocities of 400 600 m/s. Their modeling requires a three-step dissociation sequence ``Grand-Parent --> Parent --> Daughter'' to produce the observed molecules. The rotational light curve for each species is explained in terms of a single model with three sources. The dust component can however not easily be explained that way. [less ▲]

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See detailComet C/2006 P1 (McNaught)
Jehin, Emmanuel ULg; Manfroid, Jean ULg; Snodgrass, C. et al

in Central Bureau Electronic Telegrams (CBETs) (2007), 832

CBET 832 available at Central Bureau for Astronomical Telegrams.

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See detailThe impact and rotational light curves of Comet 9P/Tempel 1
Manfroid, Jean ULg; Hutsemekers, Damien ULg; Jehin, Emmanuel ULg et al

in Icarus: International Journal of Solar System Studies (2007), 191

UVES and HIRES high-resolution spectra of Comet 9P/Tempel 1 are used to investigate the impact and rotational light curves of various species with a view toward building a simple model of the distribution ... [more ▼]

UVES and HIRES high-resolution spectra of Comet 9P/Tempel 1 are used to investigate the impact and rotational light curves of various species with a view toward building a simple model of the distribution and activity of the sources. The emission by OH, NH, CN, C[SUB]3[/SUB], CH, C[SUB]2[/SUB], NH[SUB]2[/SUB], and OI, are analyzed, as well as the light scattered by the dust. It is found that a simple model reproduces fairly well the impact light curves of all species combining the production of the observed molecules and the expansion of the material throughout the slit. The impact light curves are consistent with velocities of 400 600 m/s. Their modeling requires a three-step dissociation sequence ``Grand-Parent --> Parent --> Daughter'' to produce the observed molecules. The rotational light curve for each species is explained in terms of a single model with three sources. The dust component can however not easily be explained that way. [less ▲]

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See detailComet C/2006 P1 (McNaught)
Snodgrass, C.; Fitzsimmons, A.; Hainaut, O. et al

in Central Bureau Electronic Telegrams (CBETs) (2007), 832

CBET 832 available at Central Bureau for Astronomical Telegrams.

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See detailNuclear spin temperature of ammonia in Comet 9P/Tempel 1 before and after the Deep Impact event
Kawakita, Hideyo; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Icarus: International Journal of Solar System Studies (2007), 191

The Deep Impact mission succeeded in excavating inner materials from the nucleus of Comet 9P/Tempel 1 on 2005 July 04 (at 05:52 UT). Comet 9P/Tempel 1 is one of Jupiter family short period comets, which ... [more ▼]

The Deep Impact mission succeeded in excavating inner materials from the nucleus of Comet 9P/Tempel 1 on 2005 July 04 (at 05:52 UT). Comet 9P/Tempel 1 is one of Jupiter family short period comets, which might originate in the Kuiper belt region in the solar nebula. In order to characterize the comet and to support the mission from the ground-based observatory, optical high-dispersion spectroscopic observations were carried out with the echelle spectrograph (UVES) mounted on the 8-m telescope VLT (UT2) before and after the Deep Impact event. Ortho-to-para abundance ratios (OPRs) of cometary ammonia were determined from the NH[SUB]2[/SUB] emission spectra. The OPRs of ammonia on July 3.996 UT and 4.997 UT were derived to be 1.28±0.07 (nuclear spin temperature: T[SUB][/SUB]=24±2 K) and 1.26±0.08 (T[SUB][/SUB]=25±2 K), respectively. There is no significant change between before and after the impact. Actually, most materials ejected from the impact site could have moved away from the nucleus on July 4.997 UT, about 17 h after the impact. However, a small fraction of the ejected materials might remain in the slit of UVES instrument at that time because an excess of about 20% in the NH[SUB]2[/SUB] emission flux is observed above the normal activity level was found [Manfroid, J., Hutsemékers, D., Jehin, E., Cochran, A.L., Arpigny, C., Jackson, W.M., Meech, K.J., Schulz, R., Zucconi, J.-M., 2007. Icarus. This issue]. If the excess of NH[SUB]2[/SUB] on July 04.997 UT was produced from icy materials excavated by the Deep Impact, then an upper-limit of the ammonia OPR would be 1.75 (T[SUB][/SUB]>17 K) for those materials. On the other hand, the OPR of ammonia produced from the quiescent sources was similar to that of the Oort cloud comets observed so far. This fact may imply that physical conditions where cometary ices formed were similar between Comet 9P/Tempel 1 and the Oort cloud comets. [less ▲]

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See detailThe Dusty Young Universe: photometry and spectroscopy of quasars at z > 2
Meisenheimer, K.; Hutsemekers, Damien ULg; Tacconi, L. et al

Poster (2007)

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See detailObservations of comet McNaught from La Silla
Snodgrass, C.; Jehin, Emmanuel ULg; Fitzsimmons, A. et al

Poster (2007)

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See detailThe Dusty Young Universe
Meisenheimer, K.; Dannerbauer, H.; Klaas, U. et al

Poster (2007)

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See detailThe atypical emission-line star Hen 3-209
Nazé, Yaël ULg; Rauw, Grégor ULg; Hutsemekers, Damien ULg et al

in Monthly Notices of the Royal Astronomical Society (2006), 371(4), 1594-1600

We analyse observations, spanning 15 yr, dedicated to the extreme emission-line object Hen 3-209. Our photometric data indicate that the luminosity of the star undergoes marked variations with a peak-to ... [more ▼]

We analyse observations, spanning 15 yr, dedicated to the extreme emission-line object Hen 3-209. Our photometric data indicate that the luminosity of the star undergoes marked variations with a peak-to-peak amplitude of 0.65 mag. These variations are recurrent, with a period of 16.093 +/- 0.005 d. The spectrum of Hen 3-209 is peculiar with many different lines (H I, He I, Fe II,. showing P Cygni profiles. The line profiles are apparently changing in harmony with the photometry. The spectrum also contains [O III] lines that display a saddle profile topped by three peaks, with a maximum separation of about 600 km s(-1). Hen 3-209 is most likely an evolved luminous object suffering from mass ejection events and maybe belonging to a binary system. [less ▲]

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See detailDeep Impact: High-Resolution Optical Spectroscopy with the ESO VLT and the Keck I Telescope
Jehin, Emmanuel ULg; Manfroid, Jean ULg; Hutsemekers, Damien ULg et al

in Astrophysical Journal (2006), 641(Letters), 145-148

We report on observations of comet 9P/Tempel 1 carried out before, during, and after the NASA Deep Impact event (UT July 4), with the optical spectrometers UVES and HIRES mounted on the telescopes Kueyen ... [more ▼]

We report on observations of comet 9P/Tempel 1 carried out before, during, and after the NASA Deep Impact event (UT July 4), with the optical spectrometers UVES and HIRES mounted on the telescopes Kueyen of the ESO VLT (Chile) and Keck I on Mauna Kea (Hawaii), respectively. A total observing time of about 60 hr, distributed over 15 nights around the impact date, allowed us (1) to find a periodic variation of 1.709 +/- 0.009 days in the CN and NH flux, explained by the presence of two major active regions; (2) to derive a lifetime >~5 × 10[SUP]4[/SUP] s (at 1.5 AU) for the parent of the CN radical from a simple modeling of the CN light curve after the impact; (3) to follow the gas and dust spatial profiles' evolution during the 4 hr following the impact and derive the projected velocities (400 and 150 m s[SUP]-1[/SUP], respectively); and (4) to show that the material released by the impact has the same carbon and nitrogen isotopic composition as the surface material ([SUP]12[/SUP]C/[SUP] 13[/SUP]C = 95 +/- 15 and [SUP]14[/SUP]N/[SUP]15[/SUP]N = 145 +/- 20). [less ▲]

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See detailMulti-wavelength study of the gravitational lens system RXS J113155.4-123155. I. Multi-epoch optical and near infrared imaging
Sluse, Dominique ULg; Claeskens, Jean-François ULg; Altieri, B. et al

in Astronomy and Astrophysics (2006), 449

Aims.RXS J113155.4-123155 (z=0.66) is a quadruply imaged lensed quasar with a resolved Einstein Ring. The goal of this paper is to provide a full characterization of this system, and more particularly ... [more ▼]

Aims.RXS J113155.4-123155 (z=0.66) is a quadruply imaged lensed quasar with a resolved Einstein Ring. The goal of this paper is to provide a full characterization of this system, and more particularly accurate astrometry and photometry. These observational constraints constitute a mandatory ingredient for the precise determination of the lens mass profile, the derivation of the Hubble constant H[SUB]0[/SUB] from time delay measurements and investigations on the presence of massive substructures in the lensing galaxy.Methods.Visible and near-infrared imaging observations of RXS J113155.4-123155 were carried out at various epochs using several ground based telescopes and the HST. The frames have been deconvolved using the MCS algorithm. A Singular Isothermal Ellipsoid (SIE) + external shear has been used to model the lensing galaxy potential. Results. MCS deconvolution enables us to separate the flux of the QSO (point-like images) from that of its host galaxy and to accurately track the flux variations of the point-like images in various filters. The deconvolved frames unveil several multiply imaged structures in the Einstein ring and an unidentified object in the vicinity of the lensing galaxy. We discuss the lightcurves and the chromatic flux ratio variations and deduce that both intrinsic variability and microlensing took place during a span longer than one year. We demonstrate that microlensing may easily account for the so called anomalous flux ratios presented in the discovery paper. However, the observed flux ratios are still poorly reproduced when modeling the lens potential with a SIE+shear. We argue that this disagreement can hardly be explained by milli-lensing caused by substructures in the lensing galaxy. A solution proposed in Paper II consists in a more complex lens model including an octupole term to the lens gravitational potential. [less ▲]

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See detailProbing the existence of axions with the polarization of objects at cosmological distances
Hutsemekers, Damien ULg

Conference (2006)

Photon - axion conversion within a magnetic field over cosmological distances can affect the polarization of distant objects like quasars. We report the observation of large-scale alignments of quasar ... [more ▼]

Photon - axion conversion within a magnetic field over cosmological distances can affect the polarization of distant objects like quasars. We report the observation of large-scale alignments of quasar polarization vectors as well as a rotation of their polarization angles with distance. This effect might be due to the presence of axions along the line of sight. [less ▲]

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See detailLarge Scale Correlations of Quasar Polarization Vectors: Hints of Extreme Scale Structures?
Cabanac, R. A.; Hutsemekers, Damien ULg; Sluse, Dominique ULg et al

in Astronomical Polarimetry: Current Status and Future Directions. ASPC 343 (2005, December 01)

A survey measuring quasar polarization vectors has been started in two regions towards the North and South Galactic Poles. Here, we review the discovery of significant correlations of orientations of ... [more ▼]

A survey measuring quasar polarization vectors has been started in two regions towards the North and South Galactic Poles. Here, we review the discovery of significant correlations of orientations of polarization vectors over huge angular distances. We report new results including a larger sample of the quasars confirming the existence of coherent orientations at redshifts z>1. [less ▲]

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See detailMapping extreme-scale alignments of quasar polarization vectors
Hutsemekers, Damien ULg; Cabanac, R.; Lamy, H. et al

in Astronomy and Astrophysics (2005), 441

Based on a new sample of 355 quasars with significant optical polarization and using complementary statistical methods, we confirm that quasar polarization vectors are not randomly oriented over the sky ... [more ▼]

Based on a new sample of 355 quasars with significant optical polarization and using complementary statistical methods, we confirm that quasar polarization vectors are not randomly oriented over the sky with a probability often in excess of 99.9%. The polarization vectors appear coherently oriented or aligned over huge ( 1 Gpc) regions of the sky located at both low (z Ë 0.5) and high (z Ë 1.5) redshifts and characterized by different preferred directions of the quasar polarization. In fact, there seems to exist a regular alternance along the line of sight of regions of randomly and aligned polarization vectors with a typical comoving length scale of 1.5 Gpc. Furthermore, the mean polarization angle bartheta appears to rotate with redshift at the rate of 30° per Gpc. The symmetry of the the bartheta -z relation is mirror-like, the mean polarization angle rotating clockwise with increasing redshift in North Galactic hemisphere and counter-clockwise in the South Galactic one. These characteristics make the alignment effect difficult to explain in terms of local mechanisms, namely a contamination by interstellar polarization in our Galaxy. While interpretations like a global rotation of the Universe can potentially explain the effect, the properties we observe qualitatively correspond to the dichroism and birefringence predicted by photon-pseudoscalar oscillation within a magnetic field. Interestingly, the alignment effect seems to be prominent along an axis not far from preferred directions tentatively identified in the Cosmic Microwave Background maps. Although many questions and more particularly the interpretation of the effect remain open, alignments of quasar polarization vectors appear as a promising new way to probe the Universe and its dark components at extremely large scales. [less ▲]

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See detailDeep Impact: Observations from a Worldwide Earth-Based Campaign
Meech, K. J.; Ageorges, N.; A'Hearn, M. F. et al

in Science (2005), 310

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign ... [more ▼]

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics. [less ▲]

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See detailIsotopic abundances of carbon and nitrogen in Jupiter-family and Oort Cloud comets
Hutsemekers, Damien ULg; Manfroid, Jean ULg; Jehin, Emmanuel ULg et al

in Astronomy and Astrophysics (2005), 440(Letters), 21-24

The [SUP]12[/SUP]C[SUP]14[/SUP]N/[SUP]12[/SUP]C[SUP]15[/SUP]N and [SUP]12[/SUP]C[SUP]14[/SUP]N/[SUP]13[/SUP]C[SUP]14[/SUP]N isotopic ratios are determined for the first time in a Jupiter-family comet, 88P ... [more ▼]

The [SUP]12[/SUP]C[SUP]14[/SUP]N/[SUP]12[/SUP]C[SUP]15[/SUP]N and [SUP]12[/SUP]C[SUP]14[/SUP]N/[SUP]13[/SUP]C[SUP]14[/SUP]N isotopic ratios are determined for the first time in a Jupiter-family comet, 88P/1981 Q1 Howell, and in the chemically peculiar Oort Cloud comet C/1999 S4 (LINEAR). By comparing these measurements to previous ones derived for six other Oort Cloud comets (including one of Halley-type), we find that both the carbon and nitrogen isotopic ratios are constant within the uncertainties. The mean values are [SUP]12[/SUP]C/[SUP]13[/SUP]C ~= 90 and [SUP]14[/SUP]N/[SUP]15[/SUP]N ~=145 for the eight comets. These results strengthen the view that CN radicals originate from refractory organics formed in the protosolar molecular cloud and subsequently incorporated in comets. [less ▲]

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See detailAlignments of quasar polarization vectors (Hutsemekers+, 2005)
Hutsemekers, Damien ULg; Cabanac, R.; Lamy, H. et al

Textual, factual or bibliographical database (2005)

The table contains linear polarization measurements for 355 QSOs. (3 data files).

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