Publications of Jean Manfroid
Bookmark and Share    
Full Text
See detailL’origine du télescope (I)
Manfroid, Jean ULiege

Article for general public (2013)

Detailed reference viewed: 10 (0 ULiège)
Full Text
See detailBook review: Les mots du ciel (D. Kunth)
Manfroid, Jean ULiege

Article for general public (2013)

Detailed reference viewed: 13 (0 ULiège)
Full Text
See detailLes miroirs ardents
Manfroid, Jean ULiege

Article for general public (2013)

Detailed reference viewed: 12 (1 ULiège)
Full Text
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

Astéroïdes et vie;Curiosity; CO2 et vie; HD40307; Fomalhaut b; Fond cosmique infrarouge; Fleming 1

Detailed reference viewed: 7 (1 ULiège)
Full Text
See detailLes observateurs
Manfroid, Jean ULiege

Article for general public (2012)

Coopération amateurs professionnels

Detailed reference viewed: 9 (0 ULiège)
Full Text
See detailIl y a 40 ans, une comète liégeoise
Manfroid, Jean ULiege

Article for general public (2012)

Detailed reference viewed: 14 (3 ULiège)
Full Text
See detailAlbedo and atmospheric constraints of dwarf planet Makemake from a stellar occultation
Ortiz, J. L.; Sicardy, B.; Braga-Ribas, F. et al

in Nature (2012), 491

Pluto and Eris are icy dwarf planets with nearly identical sizes, comparable densities and similar surface compositions as revealed by spectroscopic studies. Pluto possesses an atmosphere whereas Eris ... [more ▼]

Pluto and Eris are icy dwarf planets with nearly identical sizes, comparable densities and similar surface compositions as revealed by spectroscopic studies. Pluto possesses an atmosphere whereas Eris does not; the difference probably arises from their differing distances from the Sun, and explains their different albedos. Makemake is another icy dwarf planet with a spectrum similar to Eris and Pluto, and is currently at a distance to the Sun intermediate between the two. Although Makemake's size (1,420+/-60km) and albedo are roughly known, there has been no constraint on its density and there were expectations that it could have a Pluto-like atmosphere. Here we report the results from a stellar occultation by Makemake on 2011 April 23. Our preferred solution that fits the occultation chords corresponds to a body with projected axes of 1,430+/-9km (1σ) and 1,502+/-45km, implying a V-band geometric albedo p[SUB]V[/SUB] = 0.77+/-0.03. This albedo is larger than that of Pluto, but smaller than that of Eris. The disappearances and reappearances of the star were abrupt, showing that Makemake has no global Pluto-like atmosphere at an upper limit of 4-12nanobar (1σ) for the surface pressure, although a localized atmosphere is possible. A density of 1.7+/-0.3gcm[SUP]-3[/SUP] is inferred from the data. [less ▲]

Detailed reference viewed: 78 (3 ULiège)
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

Cinquantenaire de l’ESO;Constante de Hubble; Une comète brillante dans un an ?; Cratère Eltanin

Detailed reference viewed: 11 (0 ULiège)
Full Text
See detailCharon's Size And Orbit From Double Stellar Occultations
Sicardy, Bruno; Braga-Ribas, F.; Widemann, T. et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2012, October 01)

Stellar occultations of a same star by both Pluto and Charon (double events) yield instantaneous relative positions of the two bodies projected in the plane of the sky, at 10km-level accuracy. Assuming a ... [more ▼]

Stellar occultations of a same star by both Pluto and Charon (double events) yield instantaneous relative positions of the two bodies projected in the plane of the sky, at 10km-level accuracy. Assuming a given pole orientation for Charon's orbit, double events provide the satellite plutocentric distance r at a given orbital longitude L (counted from the ascending node on J2000 mean equator), and finally, constraints on its orbit. A double event observed on 22 June 2008 provides r=19,564+/-14 km at L=153.483+/-0.071 deg. (Sicardy et al. 2011), while another double event observed on 4 June 2011 yields: r=19,586+/-15 km at L = 343.211+/-0.072 deg. (all error bars at 1-sigma level). These two positions are consistent with a circular orbit for Charon, with a semi-major axis of a=19,575+\-10 km. This can be compared to the circular orbit found by Buie et al. (2012), based on Hubble Space Telescope data, with a=19,573+/-2 km. The 4 June 2011 stellar occultation provides 3 chords across Charon, from which a radius of Rc= 602.4+/-1.6 km is derived. This value can be compared to that obtained from the 11 July 2005 occultation: Rc= 606.0+/-1.5 km (Person et al. 2006) and Rc= 603.6+/-1.4 km (Sicardy et al. 2006). A third double event, observed on 23 June 2011 is under ongoing analysis, and will be presented. Buie et al. (2012), AJ 144, 15-34 (2012) Person et al, AJ 132, 1575-1580 (2006) Sicardy et al., Nature 439, 52-54 (2006) Sicardy et al., AJ 141, 67-83 (2011) B.S. thanks ANR "Beyond Neptune II". L.A.Y. acknowledges support by NASA, New Horizons and National Geographic grants. We thank B. Barnard, M.J. Brucker, J. Daily, C. Erikson, W. Fukunaga, C. Harlinten, C. Livermore, C. Nance, J.R. Regester, L. Salas, P. Tamblyn, R. Westhoff for help in the observations. [less ▲]

Detailed reference viewed: 46 (0 ULiège)
Full Text
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

Un amas avec un secret; Un résultat sucré enprovenance d’ALMA; Le cratère Hadley; La généalogie du Soleil révélée par les météorites; Dawn; Curiosity

Detailed reference viewed: 6 (0 ULiège)
Full Text
See detailThe 12C2/12C13C isotopic ratio in comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR)
Rousselot, P.; Jehin, Emmanuel ULiege; Manfroid, Jean ULiege et al

in Astronomy and Astrophysics (2012), 545

Context. Measuring the carbon isotope abundance ratio in comets allows one to constrain the conditions in the outer protosolar nebula. Different measurements of the [SUP]12[/SUP]C/[SUP]13[/SUP]C ratio ... [more ▼]

Context. Measuring the carbon isotope abundance ratio in comets allows one to constrain the conditions in the outer protosolar nebula. Different measurements of the [SUP]12[/SUP]C/[SUP]13[/SUP]C ratio, using various molecules, have already been published for different solar system objects, such as the Sun, the Earth, the Moon, asteroids, planets, or comets. So far, all these measurements are consistent with [SUP]12[/SUP]C/[SUP]13[/SUP]C ~ 90, but significant differences have been observed. This ratio is remarkably constant in comets (91.0 ± 3.6) for studies based on the CN radical, but it presents stronger variations in studies based on other radicals. <BR /> Aims: This paper aims at measuring the [SUP]12[/SUP]C/[SUP]13[/SUP]C ratio in two bright Oort cloud comets using the [SUP]12[/SUP]C_2 and [SUP]12[/SUP]C[SUP]13[/SUP]C emission lines and an improved method. The ratios will be compared to those obtained for the same comets with another radical, CN. <BR /> Methods: We used the (2,1) and (1,0) bandheads of the [SUP]12[/SUP]C[SUP]13[/SUP]C, near 4723 and 4745 Å to measure the [SUP]12[/SUP]C/[SUP]13[/SUP]C ratio and compared their intensity to the [SUP]12[/SUP]C_2 lines of the same bands. We developed a model for interpreting observational data obtained at high resolution (~70 000) using the 8.2-m Kueyen telescope (UT2) of the Very Large Telescope (VLT) with the Ultraviolet and Visual Echelle Spectrograph (UVES) in two comets: C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR). <BR /> Results: Our modeling has provided [SUP]12[/SUP]C/[SUP]13[/SUP]C = 85 ± 20 for C/2002 T7 (LINEAR) and 80 ± 20 for C/2001 Q4 (NEAT). These values are compatible with previous measurements performed with the CN radical. Based on observations made with ESO Telescopes at the Paranal Observatory under programmes ID 073.C-0525. [less ▲]

Detailed reference viewed: 38 (5 ULiège)
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

Trou noir intermédiaire; Étoiles massives;Formation de la Lune; Kepler-30; Gliese 581; Pluton; Petite exoplanète; Petite galaxie; Collision annoncée; Collision ancienne; Galaxies naines; Comète P/2012 NJ ... [more ▼]

Trou noir intermédiaire; Étoiles massives;Formation de la Lune; Kepler-30; Gliese 581; Pluton; Petite exoplanète; Petite galaxie; Collision annoncée; Collision ancienne; Galaxies naines; Comète P/2012 NJ (La Sagra); Galaxies noires; Curiosity [less ▲]

Detailed reference viewed: 19 (0 ULiège)
Full Text
See detailA-t-on trouvé le boson de Higgs ?
Manfroid, Jean ULiege

Article for general public (2012)

Detailed reference viewed: 32 (1 ULiège)
Full Text
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

Fomalhaut;Planètes volages; Astéroïdes; KOI-872; Phoebé; Jupiters chauds

Detailed reference viewed: 6 (0 ULiège)
Full Text
See detailZero Drift in Mean Anomaly of the Satellite of 1996 FG3 and its Implication for the BYORP Theory
Scheirich, P.; Pravec, P.; Mottola, S. et al

in Asteroids, Comets, Meteors 2012, Proceedings of the conference (2012, May 01)

An analysis of photometric observations of binary Near-Earth asteroid (175706) 1996 FG3, taken from 1996 to 2012, gave a single solution for a quadratic drift of the mean anomaly of the satellite, 0.0 deg ... [more ▼]

An analysis of photometric observations of binary Near-Earth asteroid (175706) 1996 FG3, taken from 1996 to 2012, gave a single solution for a quadratic drift of the mean anomaly of the satellite, 0.0 deg/yr^2, consistent with recent BYORP theory. [less ▲]

Detailed reference viewed: 23 (0 ULiège)
Full Text
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

L’anneau F de Saturne; Planètes rocheuses et zonehabitable; Lentilles gravitationnelles; Neutrinos volages; Compter les bulles; BOSS; Kepler; Tourbillon martien; Pointillés martiens; Bombardement; Trous ... [more ▼]

L’anneau F de Saturne; Planètes rocheuses et zonehabitable; Lentilles gravitationnelles; Neutrinos volages; Compter les bulles; BOSS; Kepler; Tourbillon martien; Pointillés martiens; Bombardement; Trous noirs voraces; Matière noire [less ▲]

Detailed reference viewed: 15 (0 ULiège)
Full Text
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

Collision dans le Dragon; Trou noir de masse intermédiaire;Zoom sur une galaxie lointaine; Les jours de Vénus s’allongent ?; Lumière cendrée; Anomalies magnétiques lunaires; Océan martien; Hercule par le ... [more ▼]

Collision dans le Dragon; Trou noir de masse intermédiaire;Zoom sur une galaxie lointaine; Les jours de Vénus s’allongent ?; Lumière cendrée; Anomalies magnétiques lunaires; Océan martien; Hercule par le VST [less ▲]

Detailed reference viewed: 12 (0 ULiège)
Full Text
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

Survivantes; Kepler-20 et KOI-961;Êta Carinae; Exo-Saturne ? ; GRAIL; Tranquillityite; H1743-322; Matière noire; ACT-CL J0102-4915; Nébuleuse Oméga

Detailed reference viewed: 6 (0 ULiège)
Full Text
See detailThe remarkable surface homogeneity of the Dawn mission target (1) Ceres
Carry, Benoît; Vernazza, Pierre; Dumas, Christophe et al

in Icarus (2012), 217

Dwarf-planet (1) Ceres is one of the two targets, along with (4) Vesta, that will be studied by the NASA Dawn spacecraft via imaging, visible and near-infrared spectroscopy, and gamma-ray and neutron ... [more ▼]

Dwarf-planet (1) Ceres is one of the two targets, along with (4) Vesta, that will be studied by the NASA Dawn spacecraft via imaging, visible and near-infrared spectroscopy, and gamma-ray and neutron spectroscopy. While Ceres' visible and near-infrared disk-integrated spectra have been well characterized, little has been done about quantifying spectral variations over the surface. Any spectral variation would give us insights on the geographical variation of the composition and/or the surface age. The only work so far was that of Rivkin and Volquardsen ([2010], Icarus 206, 327) who reported rotationally-resolved spectroscopic (disk-integrated) observations in the 2.2-4.0 μm range; their observations showed evidence for a relatively uniform surface.Here, we report disk-resolved observations of Ceres with SINFONI (ESO VLT) in the 1.17-1.32 μm and 1.45-2.35 μm wavelength ranges. The observations were made under excellent seeing conditions (0.6″), allowing us to reach a spatial resolution of ˜75 km on Ceres' surface. We do not find any spectral variation above a 3% level, suggesting a homogeneous surface at our spatial resolution. Slight variations (about 2%) of the spectral slope are detected, geographically correlated with the albedo markings reported from the analysis of the HST and Keck disk-resolved images of Ceres (Li et al. [2006], Icarus 182, 143; Carry et al. [2008], Astron. Astrophys. 478, 235). Given the lack of constraints on the surface composition of Ceres, however, we cannot assert the causes of these variations. [less ▲]

Detailed reference viewed: 22 (1 ULiège)
Full Text
See detailL'astronomie dans le monde
Manfroid, Jean ULiege

Article for general public (2012)

Rotation folle;SS Leporis; Kepler; Rayons cosmiques; Trous noirs géants; Comète Lovejoy

Detailed reference viewed: 10 (0 ULiège)