Publications of Jean Manfroid
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See detailISON (C/2012 S1)
Manfroid, Jean ULiege

Article for general public (2013)

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See detailComet dust profiles from PACS images obtained in the framework of the HSSO project
Opitom, Cyrielle ULiege; Bockelée-Morvan, D.; Hutsemekers, Damien ULiege et al

Poster (2013, October)

In the framework of the HssO project the Herschel PACS instrument acquired images of 7 comets between June 2010 and February 2013. Three of these comets have been imaged at several heliocentric distances ... [more ▼]

In the framework of the HssO project the Herschel PACS instrument acquired images of 7 comets between June 2010 and February 2013. Three of these comets have been imaged at several heliocentric distances allowing us to follow up the evolution of the dust coma . Radial profiles have been derived for each image. We measured flux densities at 70, 110 and 160 μm in order to determine the comet dust production rate. In some cases, after deconvolution by the instrumental PSF, we might have detected the nucleus signal in the central pixels. [less ▲]

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See detailTRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope)
Jehin, Emmanuel ULiege; Gillon, Michaël ULiege; Opitom, Cyrielle ULiege et al

in EPSC Abstract 2013 (2013, September 13), 8

TRAPPIST is a 60-cm robotic telescope that has been installed in June 2010 at the ESO La Silla Observatory [1]. Operated from Liège (Belgium) it is devoted to the detection and characterisation of ... [more ▼]

TRAPPIST is a 60-cm robotic telescope that has been installed in June 2010 at the ESO La Silla Observatory [1]. Operated from Liège (Belgium) it is devoted to the detection and characterisation of exoplanets and to the study of comets and other small bodies in the Solar System. We describe here the hardware and the goals of the project and give an overview of the comet production rates monitoring after three years of operations. [less ▲]

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See detailTRAPPIST monitoring of comet C/2012 F6 (Lemmon)
Opitom, Cyrielle ULiege; Jehin, Emmanuel ULiege; Manfroid, Jean ULiege et al

in EPSC Abstract 2013 (2013, September 12), 8

Comet C/2012 F6 is a long-period comet that reached perihelion on March 23, 2012. The unexpected brightness of this comet since December 2012 allowed us to obtain narrowband photometry and to study its ... [more ▼]

Comet C/2012 F6 is a long-period comet that reached perihelion on March 23, 2012. The unexpected brightness of this comet since December 2012 allowed us to obtain narrowband photometry and to study its chemical composition as well as its rotation. [less ▲]

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See detailStudy of the forbidden oxygen lines in comets at different heliocentric and nucleocentric distances
Decock, Alice ULiege; Jehin, Emmanuel ULiege; Rousselot, Philippe et al

in EPSC Abstract 2013 (2013, September 12), 8

Oxygen is an important element in the chemistry of the Solar System objects given its abundance and its presence in many molecules including H2O, which constitutes 80% of cometary ices. The analysis of ... [more ▼]

Oxygen is an important element in the chemistry of the Solar System objects given its abundance and its presence in many molecules including H2O, which constitutes 80% of cometary ices. The analysis of oxygen atoms in comets can provide information not only on the comets themselves but also on our Solar System. These atoms have been analyzed using the three forbidden oxygen lines [OI] observed in emission in the optical region at 5577 Å (the green line), 6300 Å and 6364 Å (the red lines) [1]. These lines are difficult to analyze because their detection requires high spectral and spatial resolutions. The oxygen analysis is interesting because it allows the determination of its parent molecules. [less ▲]

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See detailComets C/2012 V2 (LINEAR) and C/2013 R1 (Lovejoy)
Opitom, Cyrielle ULiege; Jehin, Emmanuel ULiege; Manfroid, Jean ULiege et al

in Central Bureau Electronic Telegrams (2013), 3659

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See detailA Herschel Study of D/H in Water in the Jupiter-family Comet 45P/Honda-Mrkos-Pajdušáková and Prospects for D/H Measurements with CCAT
Lis, D. C.; Biver, N.; Bockelée-Morvan, D. et al

in Astrophysical Journal Letters (2013), 774

We present Herschel observations of water isotopologues in the atmosphere of the Jupiter-family comet 45P/Honda-Mrkos-Pajdušáková. No HDO emission is detected, with a 3σ upper limit of 2.0 × 10[SUP]–4 ... [more ▼]

We present Herschel observations of water isotopologues in the atmosphere of the Jupiter-family comet 45P/Honda-Mrkos-Pajdušáková. No HDO emission is detected, with a 3σ upper limit of 2.0 × 10[SUP]–4[/SUP] for the D/H ratio. This value is consistent with the earlier Herschel measurement in the Jupiter-family comet 103P/Hartley 2. The canonical value of 3 × 10[SUP]–4[/SUP] measured pre-Herschel in a sample of Oort-cloud comets can be excluded at a 4.5σ level. The observations presented here further confirm that a diversity of D/H ratios exists in the comet population and emphasize the need for additional measurements with future ground-based facilities, such as CCAT, in the post-Herschel era. [less ▲]

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See detailL'astronomie dans le monde - 09
Manfroid, Jean ULiege

Article for general public (2013)

Les 15 ans du VLT; Régime hyposodique; Un nouveau type d’étoilesvariables; HD 95086 b; TW Hydrae; Naissance d’une étoile massive; EBL; Flashes radio; Naine brune; Galaxies massives manquantes; Big Bang ... [more ▼]

Les 15 ans du VLT; Régime hyposodique; Un nouveau type d’étoilesvariables; HD 95086 b; TW Hydrae; Naissance d’une étoile massive; EBL; Flashes radio; Naine brune; Galaxies massives manquantes; Big Bang; L’or et les sursauts gamma courts; Cartes UV de galaxies; Collision galactique; Trous noirs; Étoiles naines; Planète bleue; Planètes et étoiles Kepler; Détection d’exoplanètes; Disques et planètes; Toungouska; Chelyabinsk; Itokawa; L’eau de Mars; Traces sur Mars; Océan martien; Cartes de Mars; Vie microbienne sur Mars ?; Impacts martiens; Comètes Lazare; L’astéroïde P/2010 A2; Neptune; Quaoar; NGC 3783 [less ▲]

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See detailLes observateurs
Ponsard, P.; Manfroid, Jean ULiege; Lempereur, B.

Article for general public (2013)

Pollution lumineuse; Pollution lumineuse et sécuritéroutière; Des nouvelles de notre observatoire de Nandrin

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See detailThe Size, Shape, Albedo, Density, and Atmospheric Limit of Transneptunian Object (50000) Quaoar from Multi-chord Stellar Occultations
Braga-Ribas, F.; Sicardy, B.; Ortiz, J. L. et al

in Astrophysical Journal (2013), 773

We present results derived from the first multi-chord stellar occultations by the transneptunian object (50000) Quaoar, observed on 2011 May 4 and 2012 February 17, and from a single-chord occultation ... [more ▼]

We present results derived from the first multi-chord stellar occultations by the transneptunian object (50000) Quaoar, observed on 2011 May 4 and 2012 February 17, and from a single-chord occultation observed on 2012 October 15. If the timing of the five chords obtained in 2011 were correct, then Quaoar would possess topographic features (crater or mountain) that would be too large for a body of this mass. An alternative model consists in applying time shifts to some chords to account for possible timing errors. Satisfactory elliptical fits to the chords are then possible, yielding an equivalent radius R [SUB]equiv[/SUB] = 555 ± 2.5 km and geometric visual albedo p[SUB]V[/SUB] = 0.109 ± 0.007. Assuming that Quaoar is a Maclaurin spheroid with an indeterminate polar aspect angle, we derive a true oblateness of \epsilon = 0.087^{+0.0268}_{-0.0175}, an equatorial radius of 569^{+24}_{-17} km, and a density of 1.99 ± 0.46 g cm[SUP]–3[/SUP]. The orientation of our preferred solution in the plane of the sky implies that Quaoar's satellite Weywot cannot have an equatorial orbit. Finally, we detect no global atmosphere around Quaoar, considering a pressure upper limit of about 20 nbar for a pure methane atmosphere. [less ▲]

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See detailForbidden oxygen lines in comets at various heliocentric distances
Decock, Alice ULiege; Jehin, Emmanuel ULiege; Hutsemekers, Damien ULiege et al

in Astronomy and Astrophysics (2013), 555

We present a study of the three forbidden oxygen lines [OI] located in the optical region - i.e., 5577.339 Å (the green line), 6300.304 Å and 6363.776 Å (the two red lines) - in order to better understand ... [more ▼]

We present a study of the three forbidden oxygen lines [OI] located in the optical region - i.e., 5577.339 Å (the green line), 6300.304 Å and 6363.776 Å (the two red lines) - in order to better understand the production of these atoms in cometary atmospheres. The analysis is based on 48 high-resolution and high signal-to-noise spectra collected with UVES at the ESO VLT between 2003 and 2011 referring to 12 comets of different origins observed at various heliocentric distances. The flux ratio of the green line to the sum of the two red lines is evaluated to determine the parent species of the oxygen atoms by comparison with theoretical models. This analysis confirms that, at about 1 AU, H[SUB]2[/SUB]O is the main parent molecule producing oxygen atoms. At heliocentric distances >2.5 AU, this ratio changes rapidly, an indication that other molecules are starting to contribute. The most abundant species after H[SUB]2[/SUB]O in the coma, CO and CO[SUB]2[/SUB], are good candidates, and the ratio is used to estimate their abundances. We found that the CO[SUB]2[/SUB] abundance relative to H[SUB]2[/SUB]O in comet C/2001 Q4 (NEAT) observed at 4 AU can be as high as ~70%. The intrinsic widths of the oxygen lines were also measured. The green line is on average about 1 km s[SUP]-1[/SUP] broader than the red lines, while the theory predicts that the red lines are broader. This might be due to the nature of the excitation source or to a contribution of CO[SUB]2[/SUB] as the parent molecule of the 5577.339 Å line. At 4 AU, we found that the width of the green and red lines in comet C/2001 Q4 are the same, which could be explained if CO[SUB]2[/SUB] becomes the main contributor to the three [OI] lines at high heliocentric distances. Based on observations made with ESO Telescope at the La Silla Paranal Observatory under programs ID 268.C-5570, 270.C-5043, 073.C-0525, 274.C-5015, 075.C-0355, 080.C-0615, 280.C-5053, 086.C-0958, and 087.C-0929. [less ▲]

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See detailL'astronomie dans le monde - 06
Manfroid, Jean ULiege

Article for general public (2013)

Une binaire remarquable; Collision de galaxies;La nébuleuse planétaire C1295; ALMA (suite); Couple massif; Astéroïdes lointains; L’eau de Jupiter; Occultation par Pluton; Super-Terres; Première image ... [more ▼]

Une binaire remarquable; Collision de galaxies;La nébuleuse planétaire C1295; ALMA (suite); Couple massif; Astéroïdes lointains; L’eau de Jupiter; Occultation par Pluton; Super-Terres; Première image d’une planète massive autour d’une étoile double; Tempête au pôle de Saturne [less ▲]

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See detailComets C/2012 F6 (Lemmon), C/2013 E2 (Iwamoto), and 63P/Wild
Opitom, Cyrielle ULiege; Jehin, Emmanuel ULiege; Manfroid, Jean ULiege et al

in Central Bureau Electronic Telegrams (2013), 3530

CBET 3530 available at Central Bureau for Astronomical Telegrams.

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See detailL'astronomie dans le monde - 05
Manfroid, Jean ULiege

Article for general public (2013)

Mars; ISON; Un troyen d’Uranus; Titan; Europe; Planck révèle un Univers presque parfait; WISE J1049-5319; GRAIL; ALMA; VIPERS; Supernova lointaine; Supernovæ Ia

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See detailL'astronomie dans le monde - 04
Manfroid, Jean ULiege

Article for general public (2013)

Rayons cosmiques; Le bolide de Chelyabinsk; L’astéroïde 2012 DA14;Kepler-37b; G0.253+0.016; Geysers galactiques; La distance du Grand Nuage

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See detailComets C/2012 F6 (Lemmon) and C/2011 L4 (Panstarrs)
Opitom, Cyrielle ULiege; Jehin, Emmanuel ULiege; Manfroid, Jean ULiege et al

in Central Bureau Electronic Telegrams (2013), 3433

CBET 3433 available at Central Bureau for Astronomical Telegrams.

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See detailL'astronomie dans le monde - 03
Manfroid, Jean ULiege

Article for general public (2013)

Transit vénusien; Tau Ceti; Toutatis; Titan; GRAIL; Kepler; Voie Lactée

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See detailL’origine du télescope (II)
Manfroid, Jean ULiege

Article for general public (2013)

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See detailL'astronomie dans le monde - 02
Manfroid, Jean ULiege

Article for general public (2013)

Transit vénusien; Tau Ceti; Toutatis; Titan; GRAIL; Kepler; Voie Lactée

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See detailL'astronomie dans le monde - 01
Manfroid, Jean ULiege

Article for general public (2013)

Polaris; Trou noir géant; Jet record; Mercure; Makémaké

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