References of "Hutsemekers, Damien"
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See detailOccultation by (136199) Eris
Jehin, Emmanuel ULg; Manfroid, Jean ULg; Gillon, Michaël ULg et al

in International Astronomical Union Circulars [=IAUCs] (2010), 9184

E. Jehin, J. Manfroid, M. Gillon, D. Hutsemekers, and P. Magain report that they observed an occultation of a star of magnitude I about 15.2 by the dwarf planet Eris (then at V about 18.7) on Nov. 6 using ... [more ▼]

E. Jehin, J. Manfroid, M. Gillon, D. Hutsemekers, and P. Magain report that they observed an occultation of a star of magnitude I about 15.2 by the dwarf planet Eris (then at V about 18.7) on Nov. 6 using the new telescope TRAPPIST at the European Southern Observatory (La Silla). A series of 3-s exposures of a field of size 3' x 3' (1".3/pixel) were secured in fast-readout mode (with a deadtime of 1.5 s), starting at 01h50m UT for one hour. Seven frames centered at 02h19m34s UT allowed them to derive the start of the occultation as 02h19m16s.75 +/- 0s.75 and the end as 02h19m47s.6 +/- 0s.2, for a total occultation time of 30.4 +/- 1.0 seconds. The predictions (see above) made by the Rio de Janeiro group (Assafin et al., Nov. 5) and by J. L. Ortiz estimated the time of the occultation around 02h18m UT for Chile, in good agreement with the observations. During the occultation, a point source is detected with a magnitude corresponding to that of Eris. A small flux increase was also seen at the middle of the occultation, which might result from refraction in Eris' atmosphere (Elliot and Olkin 1996, Ann. Rev. Earth Planet. Sci. 24, 89). Eris is by far the most-remote solar-system object observed to date via stellar occultation, with a geocentric distance of about 96 AU. TRAPPIST is a project driven by the University of Liege, in close collaboration with the Observatory of Geneva, supported by the Belgian Fund for Scientific Research and the Swiss National Science Foundation. [less ▲]

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See detailWater production in comet 81P/Wild 2 as determined by Herschel/HIFI
de Val-Borro, M.; Hartogh, P.; Crovisier, J. et al

in Astronomy and Astrophysics (2010), 521(Letters), 501-5

The high spectral resolution and sensitivity of Herschel/HIFI allows for the detection of multiple rotational water lines and accurate determinations of water production rates in comets. In this Letter we ... [more ▼]

The high spectral resolution and sensitivity of Herschel/HIFI allows for the detection of multiple rotational water lines and accurate determinations of water production rates in comets. In this Letter we present HIFI observations of the fundamental 1[SUB]10[/SUB]-1[SUB]01[/SUB] (557 GHz) ortho and 1[SUB]11[/SUB]-[SUB]00[/SUB] (1113 GHz) para rotational transitions of water in comet 81P/Wild 2 acquired in February 2010. We mapped the extent of the water line emission with five point scans. Line profiles are computed using excitation models which include excitation by collisions with electrons and neutrals and solar infrared radiation. We derive a mean water production rate of 1.0 × 10[SUP]28[/SUP] molecules s[SUP]-1[/SUP] at a heliocentric distance of 1.61 AU about 20 days before perihelion, in agreement with production rates measured from the ground using observations of the 18-cm OH lines. Furthermore, we constrain the electron density profile and gas kinetic temperature, and estimate the coma expansion velocity by fitting the water line shapes. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Figure 5 (page 5) is only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailThe 3/4 July 2010 Pluto Stellar-Occultation Observations
Pasachoff, Jay M; Elliot, J. L.; Souza, S. P. et al

in Bulletin of the American Astronomical Society (2010, October 01), 42

Continuing our monitoring of Pluto's atmospheric temperature and pressure, previously shown by us to be increasing (Elliot et al., Nature 424, 165, 2003; Pasachoff et al., AJ 129, 1718, 2005) and ... [more ▼]

Continuing our monitoring of Pluto's atmospheric temperature and pressure, previously shown by us to be increasing (Elliot et al., Nature 424, 165, 2003; Pasachoff et al., AJ 129, 1718, 2005) and subsequently found by us to be leveling off (Elliot et al., AJ 134, 1, 2007), we report on a stellar occultation by Pluto of UCAC2 mag=15.3, observed from South America and Africa on 4 July 2010 UT. Success was achieved with a 0.45 m at Cerro Calan using one of our POETS (Portable Occultation, Eclipse, and Transit System; Souza et al. PASP 118, 1550, 2006), a 1.0 SMARTS (Small and Medium Aperture Research Telescope System) at Cerro Tololo, four 0.6 m telescopes of PROMPT (Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes) on Cerro Tololo, and TRAPPIST's (TRansiting Planets and Planetesimals Small Telescope) 0.6-m telescope on La Silla in Chile; the 0.35 m telescope of U. Ponta Grossa, Brazil; and the 0.75-m ATOM (Automatic Telescope for Optical Monitoring), Namibia, using POETS. Winds prevented opening the 6.5 m Magellan/Clay telescope on Las Campanas, Chile, with its own frame-transfer camera, and clouds obscured the 1.9 m telescope at Sutherland, South Africa, which had POETS. With shadow velocity 23.6 km/s, it was a rapid event: maximum occultation <2 minutes. The observations were supported in part by grants NNX08AO50G to Williams College and NNX10AB27G to MIT from NASA's Planetary Astronomy Division, and NNH08AI17I to USNO for astrometry. Student participation was supported in part by NASA's Massachusetts Space Grant and NSF's REU. Japan's government donated U. Chile's Cerro Calan Goto telescope. PROMPT observations were made possible by the Robert Martin Ayers Science Fund. TRAPPIST is a project driven by the University of Liège, in close collaboration with the Observatory of Geneva, supported by the Belgian Fund for Scientific Research and the Swiss National Science Foundation. [less ▲]

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See detailOPRs of Ammonia versus 14N/15N Ratios in CN in 15 Comets
Shinnaka, Yoshiharu; Kawakita, H.; Kobayashi, H. et al

in Bulletin of the American Astronomical Society (2010, October 01), 42

The solar system was formed from interstellar matter 4.6 Gyrs ago and comets are considered as remnants of icy planetesimals formed in the early solar system. One of interesting primordial characters of ... [more ▼]

The solar system was formed from interstellar matter 4.6 Gyrs ago and comets are considered as remnants of icy planetesimals formed in the early solar system. One of interesting primordial characters of cometary ice is an ortho-to-para abundance ratio (OPR) of molecules such as H2O, NH3, etc. The OPR probably indicates the molecular formation temperatures in the solar nebula or in the pre-solar molecular cloud. We determined the OPRs of ammonia by using the high dispersion optical spectra of NH2 in 15 comets: C/1995 O1 (Hale-Bopp), C/1999 S4 (LINEAR), C/2001 A2 (LINEAR), C/2000 WM1 (LINEAR), 153P/Ikeya-Zhang, C/2002 V1 (NEAT), C/2002 X5 (Kudo-Fujikawa), C/2002 Y1 (Juels-Holvorcem), C/2001 Q4 (NEAT), C/2002 T7 (LINEAR), C/2003 K4 (LINEAR), 8P/Tuttle, 88P/Howell, 9P/Tempel 1, and 73P-B and -C/Schwassmann-Wachmann 3. The observations were mainly carried out by the Ultraviolet and Visual Echelle Spectrograph (UVES) mounted on the Very Large Telescope (VLT) in Chile. Other telescopes/instruments were also used in some cases. The OPRs of ammonia are determined from OPRs of NH2 (0,9,0) ro-vibronic band around 600 nm. Although absorption lines (by the telluric atmosphere) and cometary C2 emission lines blended affected to NH2 emission lines in this region, we removed them in our analysis. The determined OPRs of ammonia clustered around 30K but not in the cases of 73P-B and -C. This situation is very similar to that of 14N/15N ratios in CN (i.e., 73P-B and -C are quite peculiar relative to other comets). We discuss about the relationship between the OPRs of ammonia and 14N/15N ratios in CN in these 15 comets. Our results indicate the formation of materials at relatively higher temperatures for 73P-B and -C than other comets. [less ▲]

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See detailComet 29P/Schwassmann-Wachmann Observed with the Herschel Space Observatory: Detection of Water Vapour and Dust Far-IR Thermal Emission
Bockelee-Morvan, Dominique; Biver, N.; Crovisier, J. et al

in Bulletin of the American Astronomical Society (2010, October 01), 42

The distant comet 29P/Schwassmann-Wachmann was observed with the HIFI, PACS and SPIRE instruments aboard the Herschel Space Observatory, as part of the guaranteed time key programme "Water and related ... [more ▼]

The distant comet 29P/Schwassmann-Wachmann was observed with the HIFI, PACS and SPIRE instruments aboard the Herschel Space Observatory, as part of the guaranteed time key programme "Water and related chemistry in the Solar System" (KP-GT HssO). Supporting observations of the 230 GHz CO line were carried out with the IRAM 30-m telescope. The HIFI observations of the 557 GHz H2O line were performed on 19.05 April 2010, about 2 days after a major outburst, and on 11.02 May 2010, when 29P was in a more quiescent phase. H2O was detected on both dates with a production rate corresponding to about 1/10th the CO production, assuming near-nucleus production. The H2O line shape is consistent with release of water vapour from icy grains. PACS and SPIRE imaging data from 70 to 500 micrometers were acquired mid-June 2010 when the comet was in a quiescent phase. The continuum emission detected in the 70-μm and 160-μm PACS images is weakly extended with respect to the PSF, suggesting a major contribution from the nucleus or from slowly moving large grains. [less ▲]

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See detailMicrolensing in H1413+117: disentangling line profile emission and absorption in a broad absorption line quasar
Hutsemekers, Damien ULg; Borguet, Benoît ULg; Sluse, Dominique ULg et al

in Astronomy and Astrophysics (2010), 519

On the basis of 16 years of spectroscopic observations of the four components of the gravitationally lensed broad absorption line (BAL) quasar H1413+117, covering the ultraviolet to visible rest-frame ... [more ▼]

On the basis of 16 years of spectroscopic observations of the four components of the gravitationally lensed broad absorption line (BAL) quasar H1413+117, covering the ultraviolet to visible rest-frame spectral range, we analyze the spectral differences observed in the P Cygni-type line profiles and have used the microlensing effect to derive new clues to the BAL profile formation. We first find that the absorption gradually decreases with time in all components and that this intrinsic variation is accompanied by a decrease in the intensity of the emission. We confirm that the spectral differences observed in component D can be attributed to a microlensing effect lasting at least a decade. We show that microlensing magnifies the continuum source in image D, leaving the emission line region essentially unaffected. We interpret the differences seen in the absorption profiles of component D as the result of an emission line superimposed onto a nearly black absorption profile. We also find that the continuum source and a part of the broad emission line region are likely de-magnified in component C, while components A and B are not affected by microlensing. Differential dust extinction is measured between the A and B lines of sight. We show that microlensing of the continuum source in component D has a chromatic dependence compatible with the thermal continuum emission of a standard Shakura-Sunyaev accretion disk. Using a simple decomposition method to separate the part of the line profiles affected by microlensing and coming from a compact region from the part unaffected by this effect and coming from a larger region, we disentangle the true absorption line profiles from the true emission line profiles. The extracted emission line profiles appear double-peaked, suggesting that the emission is occulted by a strong absorber, narrower in velocity than the full absorption profile, and emitting little by itself. We propose that the outflow around H1413+117 is constituted by a high-velocity polar flow and a denser, lower velocity disk seen nearly edge-on. Finally, we report on the first ground-based polarimetric measurements of the four components of H1413+117. Based on observations made with the Canada-France-Hawaii Telescope (Hawaii), with ESO Telescopes at the Paranal Observatory (Chile) and with the NASA/ESA Hubble Space Telescope, and obtained from the data archive at the Space Telescope Institute. ESO program ID: 074.A-0152, 075.B-0675, 081.A-0023. [less ▲]

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See detailOptical circular polarization in quasars
Hutsemekers, Damien ULg; Borguet, Benoît ULg; Sluse, Dominique ULg et al

in Astronomy and Astrophysics (2010), 520(Letters), 71-5

We present new optical circular polarization measurements with typical uncertainties <0.1% for a sample of 21 quasars. All but two objects have null circular polarization. We use this result to constrain ... [more ▼]

We present new optical circular polarization measurements with typical uncertainties <0.1% for a sample of 21 quasars. All but two objects have null circular polarization. We use this result to constrain the polarization due to photon-pseudoscalar mixing along the line of sight. We detect significant (> 3σ) circular polarization in two blazars with high linear polarization and discuss the implications of this result for quasar physics. In particular, the recorded polarization degrees may be indicative of magnetic fields as strong as 1 kG or a significant contribution of inverse Compton scattering to the optical continuum. Based on observations made with ESO Telescopes at the La Silla Observatory (Chile). ESO program ID: 79.A-0625(B).Appendices are only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailHIFI observations of water in the atmosphere of comet C/2008 Q3 (Garradd)
Hartogh, P.; Crovisier, J.; de Val-Borro, M. et al

in Astronomy and Astrophysics (2010), 518(Letters), 1501-5

High-resolution far-infrared and sub-millimetre spectroscopy of water lines is an important tool to understand the physical and chemical properties of cometary atmospheres. We present observations of ... [more ▼]

High-resolution far-infrared and sub-millimetre spectroscopy of water lines is an important tool to understand the physical and chemical properties of cometary atmospheres. We present observations of several rotational ortho- and para-water transitions in comet C/2008 Q3 (Garradd) performed with HIFI on Herschel. These observations have provided the first detection of the 2[SUB]12[/SUB]-1[SUB]01[/SUB] (1669 GHz) ortho and 1[SUB]11[/SUB]-0[SUB]00[/SUB] (1113 GHz) para transitions of water in a cometary spectrum. In addition, the ground-state transition 1[SUB]10[/SUB]-1[SUB]01[/SUB] at 557 GHz is detected and mapped. By detecting several water lines quasi-simultaneously and mapping their emission we can constrain the excitation parameters in the coma. Synthetic line profiles are computed using excitation models which include excitation by collisions, solar infrared radiation, and radiation trapping. We obtain the gas kinetic temperature, constrain the electron density profile, and estimate the coma expansion velocity by analyzing the map and line shapes. We derive water production rates of 1.7-2.8 × 10[SUP]28[/SUP] s[SUP]-1[/SUP] over the range r[SUB]h[/SUB] = 1.83-1.85 AU. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Figure 5 is only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailA study of the distant activity of comet C/2006 W3 (Christensen) with Herschel and ground-based radio telescopes
Bockelée-Morvan, D.; Hartogh, P.; Crovisier, J. et al

in Astronomy and Astrophysics (2010), 518(Letters), 1491-6

Comet C/2006 W3 (Christensen) was observed in November 2009 at 3.3 AU from the Sun with Herschel.The PACS instrument acquired images of the dust coma in 70-μm and 160-μm filters and spectra covering ... [more ▼]

Comet C/2006 W3 (Christensen) was observed in November 2009 at 3.3 AU from the Sun with Herschel.The PACS instrument acquired images of the dust coma in 70-μm and 160-μm filters and spectra covering several H[SUB]2[/SUB]O rotational lines. Spectra in the range 450-1550 GHz were acquired with SPIRE. The comet emission continuum from 70 to 672 μm was measured, but no lines were detected. The spectral energy distribution indicates thermal emission from large particles and provides a measure of the size distribution index and dust production rate. The upper limit to the water production rate is compared to the production rates of other species (CO, CH[SUB]3[/SUB]OH, HCN, H[SUB]2[/SUB]S, OH) measured with the IRAM 30-m and Nançay telescopes. The coma is found to be strongly enriched in species more volatile than water, in comparison to comets observed closer to the Sun. The CO to H[SUB]2[/SUB]O production rate ratio exceeds 220%. The dust-to-gas production rate ratio is on the order of 1. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Figures 2, 5, 6 are only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailHerschel-PACS far-infrared photometry of two z > 4 quasars
Leipski, C.; Meisenheimer, K.; Klaas, U. et al

in Astronomy and Astrophysics (2010), 518(Letters), 341-4

We present Herschel far-infrared (FIR) observations of two sub-mm bright quasars at high redshift: SDSS J1148+5251 (z = 6.42) and BR 1202-0725 (z = 4.69) obtained with the PACS instrument. Both objects ... [more ▼]

We present Herschel far-infrared (FIR) observations of two sub-mm bright quasars at high redshift: SDSS J1148+5251 (z = 6.42) and BR 1202-0725 (z = 4.69) obtained with the PACS instrument. Both objects are detected in the PACS photometric bands. The Herschel measurements provide additional data points that constrain the FIR spectral energy distributions (SEDs) of both sources, and they emphasise a broad range of dust temperatures in these objects. For λ[SUB]rest[/SUB] ≲ 20 μm, the two SEDs are very similar to the average SEDs of quasars at low redshift. In the FIR, however, both quasars show excess emission compared to low-z QSO templates, most likely from cold dust powered by vigorous star formation in the QSO host galaxies. For SDSS J1148+5251 we detect another object at 160 μm with a distance of ~10´´ from the QSO. Although no physical connection between the quasar and this object can be shown with the available data, it could potentially confuse low-resolution measurements, thus resulting in an overestimate of the FIR luminosity of the z = 6.42 quasar. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. [less ▲]

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See detailA polar+equatorial wind model for broad absorption line quasars. I. Fitting the C IV BAL profiles
Borguet, Benoît ULg; Hutsemekers, Damien ULg

in Astronomy and Astrophysics (2010), 515

Context. Despite all the studies, the geometry of the wind at the origin of the blueshifted broad absorption lines (BAL) observed in nearly 20% of quasars still remains a matter of debate. <BR /> Aims: We ... [more ▼]

Context. Despite all the studies, the geometry of the wind at the origin of the blueshifted broad absorption lines (BAL) observed in nearly 20% of quasars still remains a matter of debate. <BR /> Aims: We want to see if a two-component polar+equatorial wind geometry can reproduce the typical BAL profiles observed in these objects. <BR /> Methods: We built a Monte Carlo radiative transfer code (called MCRT) to simulate the line profiles formed in a polar+equatorial wind in which the photons, emitted from a spherically symmetric core are resonantly scattered. Our goal is to reproduce typical C iv line profiles observed in BAL quasars and to identify the parameters governing the line profiles. <BR /> Results: The two-component wind model appears to be efficient in reproducing the BAL profiles from the P Cygni-type profiles to the more complex ones. Some profiles can also be reproduced with a pole-on view. Our simulations provide evidence of a high-velocity rotation of the wind around the polar axis in BAL quasars with non P Cygni-type line profiles. [less ▲]

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See detailHigh-dispersion infrared spectroscopic observations of comet 8P/Tuttle with VLT/CRIRES
Kobayashi, H.; Bockelée-Morvan, D.; Kawakita, H. et al

in Astronomy and Astrophysics (2010), 509

We report on the composition of the Halley-family comet (HFC) 8P/Tuttle investigated with high-dispersion near-infrared spectroscopic observations. The observations were carried out at the ESO VLT (Very ... [more ▼]

We report on the composition of the Halley-family comet (HFC) 8P/Tuttle investigated with high-dispersion near-infrared spectroscopic observations. The observations were carried out at the ESO VLT (Very Large Telescope) with the CRIRES instrument as part of a multi-wavelength observation campaign of 8P/Tuttle performed in late January and early February 2008. Radar observations suggested that 8P/Tuttle is a contact binary, and it was proposed that these components might be heterogeneous in chemistry. We determined mixing ratios of organic volatiles with respect to H[SUB]2[/SUB]O and found that mixing ratios were consistent with previous near infrared spectroscopic observations obtained in late December 2007 and in late January 2008. It has been suggested that because 8P/Tuttle is a contact binary, it might be chemically heterogeneous. However, we find no evidence for chemical heterogeneity within the nucleus of 8P/Tuttle. We also compared the mixing ratios of organic molecules in 8P/Tuttle with those of both other HFCs and long period comets (LPCs) and found that HCN, C[SUB]2[/SUB]H[SUB]2[/SUB], and C[SUB]2[/SUB]H[SUB]6[/SUB] are depleted whereas CH[SUB]4[/SUB] and CH[SUB]3[/SUB]OH have normal abundances. This may indicate that 8P/Tuttle was formed in a different region of the early solar nebula than other HFCs and LPCs. We estimated the conversion efficiency from C[SUB]2[/SUB]H[SUB]2[/SUB] to C[SUB]2[/SUB]H[SUB]6[/SUB] by hydrogen addition reactions on cold grains by employing the C[SUB]2[/SUB]H[SUB]6[/SUB]/(C[SUB]2[/SUB]H[SUB]6[/SUB]+C[SUB]2[/SUB]H[SUB]2[/SUB]) ratio. The C[SUB]2[/SUB]H[SUB]6[/SUB]/(C[SUB]2[/SUB]H[SUB]6[/SUB]+C[SUB]2[/SUB]H[SUB]2[/SUB]) ratio in 8P/Tuttle is consistent with the ratios found in other HFCs and LPCs within the error bars. We also discuss the source of C[SUB]2[/SUB] and CN based on our observations and conclude that the abundances of C[SUB]2[/SUB]H[SUB]2[/SUB] and C[SUB]2[/SUB]H[SUB]6[/SUB] are insufficient to explain the C[SUB]2[/SUB] abundances in comet 8P/Tuttle and that the abundance of HCN is insufficient to explain the CN abundances in the comet, so at least one additional parent is needed for each species, as pointed out in previous study. Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO Prog. 080.C-0615 and 280.C-5053).We regret to note the death of Dr. J. -M. Zucconi in 2009 May. [less ▲]

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See detailObservations of nebulae ejected by massive stars with PACS
Vamvatira-Nakou, Chloi ULg; Royer, P.; Hutsemekers, Damien ULg et al

Poster (2010)

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See detailLarge-scale coherent orientations of quasar polarisation vectors: interpretation in terms of axion-like particles
Payez, Alexandre ULg; Hutsemekers, Damien ULg; Cudell, Jean-René ULg

in AIP Conference Proceedings (2010), 1274,

The observation of redshift-dependent coherent orientations of quasar polarisation vectors over cosmological distances in some regions of the sky is reviewed. Based on a good-quality sample of 355 ... [more ▼]

The observation of redshift-dependent coherent orientations of quasar polarisation vectors over cosmological distances in some regions of the sky is reviewed. Based on a good-quality sample of 355 measured quasars, this observation seems to infer the existence of a new effect acting on light propagation on such huge distances. A solution in terms of nearly massless axion-like particles has been proposed in the literature and its current status is discussed. [less ▲]

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See detailFirst results of the HssO key programme
Hartogh, Paul; Crovisier, Jacques; Lellouch et al

in 38th COSPAR Scientific Assembly (2010)

The HssO (Herschel solar system Observations) program aims at determining the distribution, the evolution and the origin of water in Mars, the Outer Planets, Titan, Enceladus and comets, using the three ... [more ▼]

The HssO (Herschel solar system Observations) program aims at determining the distribution, the evolution and the origin of water in Mars, the Outer Planets, Titan, Enceladus and comets, using the three Herschel instruments HIFI, PACS and SPIRE. It addresses the broad topic of water and its isotopologues in planetary and cometary atmospheres. The nature of cometary activity and the thermodynamics of cometary comae will be investigated by studying water excitation in a sample of comets. The D/H ratio, the key parameter for constraining the origin and evolution of Solar System materials, will be measured for the first time in a Jupiter family comet. A comparison with existing and new measurements of D/H in Oort cloud comets will constrain the composition of pre-solar cometary grains and possibly the dynamics of the protosolar nebula. New measurements of D/H in Giant Planets, similarly constraining the composition of proto-planetary ices, will be obtained. The D/H and other isotopic ratios, diagnostics of the evolution of Mars atmosphere, will be accurately measured in H2O and CO. The role of water vapour in the atmospheric chemistry of Mars will be studied by monitoring vertical profiles of H2O and HDO and by searching for several other species (including CO and H2O isotopologues). A detailed study of the source of water in the upper atmosphere of the Giant Planets and Titan will be performed. By monitoring the water abundance, vertical profile, and input fluxes in the various objects, and when possible with the help of mapping observations, we will discriminate between the possible sources of water in the Outer Planets (interplanetary dust particles, cometary impacts, and local sources). First results on comets, Mars and the outer planets will be presented. [less ▲]

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See detailOn the circular polarisation of light from axion-photon mixing
Payez, Alexandre ULg; Cudell, Jean-René ULg; Hutsemekers, Damien ULg

in Alimi, Jean-Michel; Füzfa, André (Eds.) INVISIBLE UNIVERSE: Proceedings of the Conference. AIP Conference Proceedings 1241. (2010)

From the analysis of measurements of the linear polarisation of visible light coming from quasars, the existence of large-scale coherent orientations of quasar polarisation vectors in some regions of the ... [more ▼]

From the analysis of measurements of the linear polarisation of visible light coming from quasars, the existence of large-scale coherent orientations of quasar polarisation vectors in some regions of the sky has been reported. Here, we show that this can be explained by the mixing of the incoming photons with nearly massless pseudoscalar (axion-like) particles in extragalactic magnetic fields. We present a new treatment in terms of wave packets and discuss its implications for the circular polarisation. [less ▲]

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See detailAxion-like particles and circular polarisation of active galactic nuclei
Payez, Alexandre ULg; Cudell, Jean-René ULg; Hutsemekers, Damien ULg

in Jaeckel, Joerg; Lindner, Axel; Redondo, Javier (Eds.) Proceedings of the 5th Patras Workshop on Axions, WIMPs and WISPs PATRAS 2009 (2010)

The measurements of the linear polarisation of visible light from quasars give strong evidence for large-scale coherent orientations of their polarisation vectors in some regions of the sky. We show that ... [more ▼]

The measurements of the linear polarisation of visible light from quasars give strong evidence for large-scale coherent orientations of their polarisation vectors in some regions of the sky. We show that these observations can be explained by the mixing of the photons with very light pseudoscalar (axion-like) particles in extragalactic magnetic fields during their propagation. We present a new treatment in terms of wave packets and discuss the circular polarisation. [less ▲]

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See detailA study of the distant activity of comet C/2006 W3 (Christensen) using Herschel and ground-based radio telescopes
Bockelée-Morvan, D.; Hartogh, P.; Crovisier, J. et al

Poster (2010)

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See detailNew constraints on the delivery of cometary water and nitrogen to Earth from the 15N/14N isotopic ratio
Hutsemekers, Damien ULg; Manfroid, Jean ULg; Jehin, Emmanuel ULg et al

in Icarus: International Journal of Solar System Studies (2009), 204

New independent constraints on the amount of water delivered to Earth by comets are derived using the [SUP]15[/SUP]N/[SUP]14[/SUP]N isotopic ratio, measured to be roughly twice as high in cometary CN and ... [more ▼]

New independent constraints on the amount of water delivered to Earth by comets are derived using the [SUP]15[/SUP]N/[SUP]14[/SUP]N isotopic ratio, measured to be roughly twice as high in cometary CN and HCN as in the present Earth. Under reasonable assumptions, we find that no more than a few percent of Earthâ s water can be attributed to comets, in agreement with the constraints derived from D/H. Our results also suggest that a significant part of Earthâ s atmospheric nitrogen might come from comets. Since the [SUP]15[/SUP]N/[SUP]14[/SUP]N isotopic ratio is not different in Oort-cloud and Kuiper-belt comets, our estimates apply to the contribution of both types of objects. [less ▲]

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See detailWater and related chemistry in the solar system. A guaranteed time key programme for Herschel
Hartogh, P.; Lellouch, E.; Crovisier, J. et al

in Planetary and Space Science (2009), 57

â Water and related chemistry in the Solar Systemâ is a Herschel Space Observatory Guaranteed-Time Key Programme. This project, approved by the European Space Agency, aims at determining the distribution ... [more ▼]

â Water and related chemistry in the Solar Systemâ is a Herschel Space Observatory Guaranteed-Time Key Programme. This project, approved by the European Space Agency, aims at determining the distribution, the evolution and the origin of water in Mars, the outer planets, Titan, Enceladus and the comets. It addresses the broad topic of water and its isotopologues in planetary and cometary atmospheres. The nature of cometary activity and the thermodynamics of cometary comae will be investigated by studying water excitation in a sample of comets. The D/H ratio, the key parameter for constraining the origin and evolution of Solar System species, will be measured for the first time in a Jupiter-family comet. A comparison with existing and new measurements of D/H in Oort-cloud comets will constrain the composition of pre-solar cometary grains and possibly the dynamics of the protosolar nebula. New measurements of D/H in giant planets, similarly constraining the composition of proto-planetary ices, will be obtained. The D/H and other isotopic ratios, diagnostic of Marsâ atmosphere evolution, will be accurately measured in H[SUB]2[/SUB]O and CO. The role of water vapor in Marsâ atmospheric chemistry will be studied by monitoring vertical profiles of H[SUB]2[/SUB]O and HDO and by searching for several other species (and CO and H[SUB]2[/SUB]O isotopes). A detailed study of the source of water in the upper atmosphere of the Giant Planets and Titan will be performed. By monitoring the water abundance, vertical profile, and input fluxes in the various objects, and when possible with the help of mapping observations, we will discriminate between the possible sources of water in the outer planets (interplanetary dust particles, cometary impacts, and local sources). In addition to these inter-connected objectives, serendipitous searches will enhance our knowledge of the composition of planetary and cometary atmospheres. [less ▲]

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