Publications of Jean Manfroid     Results 1-20 of 789. 1 2 3 4 5 6 7 8 9 10   Dust modelling and dynamical study of comet 41P/Tuttle-Giacobini-Kresak during 2017 perihelion passagePozuelos Romero, Francisco José ; Jehin, Emmanuel ; Moulane, Youssef et alin Astronomy and Astrophysics (2018)Detailed reference viewed: 10 (4 ULiège) Isotopic ratios in outbursting comet C/2015 ER61Yang, Bin; Hutsemekers, Damien ; Shinnaka, Yoshiharu et alin Astronomy and Astrophysics (2018), 609Isotopic ratios in comets are critical to understanding the origin of cometary material and the physical and chemical conditions in the early solar nebula. Comet C/2015 ER61 (PANSTARRS) underwent an ... [more ▼]Isotopic ratios in comets are critical to understanding the origin of cometary material and the physical and chemical conditions in the early solar nebula. Comet C/2015 ER61 (PANSTARRS) underwent an outburst with a total brightness increase of 2 magnitudes on the night of 2017 April 4. The sharp increase in brightness offered a rare opportunity to measure the isotopic ratios of the light elements in the coma of this comet. We obtained two high-resolution spectra of C/2015 ER61 with UVES/VLT on the nights of 2017 April 13 and 17. At the time of our observations, the comet was fading gradually following the outburst. We measured the nitrogen and carbon isotopic ratios from the CN violet (0, 0) band and found that [SUP]12[/SUP]C/[SUP]13[/SUP]C = 100 ± 15, [SUP]14[/SUP]N/[SUP]15[/SUP]N = 130 ± 15. In addition, we determined the [SUP]14[/SUP]N/[SUP]15[/SUP]N ratio from four pairs of NH[SUB]2[/SUB] isotopolog lines and measured [SUP]14[/SUP]N/[SUP]15[/SUP]N = 140 ± 28. The measured isotopic ratios of C/2015 ER61 do not deviate significantly from those of other comets. [less ▲]Detailed reference viewed: 11 (2 ULiège) Stellar parameters for TRAPPIST-1Van Grootel, Valérie ; Silva Fernandes, Catarina ; Gillon, Michaël et alin Astrophysical Journal (2018), 853TRAPPIST-1 is an ultracool dwarf star transited by seven Earth-sized planets, for which thorough characterization of atmospheric properties, surface conditions encompassing habitability and internal ... [more ▼]TRAPPIST-1 is an ultracool dwarf star transited by seven Earth-sized planets, for which thorough characterization of atmospheric properties, surface conditions encompassing habitability and internal compositions is possible with current and next generation telescopes. Accurate modeling of the star is essential to achieve this goal. We aim to obtain updated stellar parameters for TRAPPIST- 1 based on new measurements and evolutionary models, compared to those used in discovery studies. We present a new measurement for the parallax of TRAPPIST-1, 82.4 $\pm$ 0.8 mas, based on 188 epochs of observations with the TRAPPIST and Liverpool Telescopes from 2013 to 2016. This revised parallax yields an updated luminosity of $L_*=(5.22\pm0.19)\times 10^{-4} L_{\odot}$, very close to the previous estimate but almost twice more precise. We next present an updated estimate for TRAPPIST-1 stellar mass, based on two approaches: mass from stellar evolution modeling, and empirical mass derived from dynamical masses of equivalently classified ultracool dwarfs in astrometric binaries. We combine them through a Monte-Carlo approach to derive a semi-empirical estimate for the mass of TRAPPIST-1. We also derive estimate for the radius by combining this mass with stellar density inferred from transits, as well as estimate for the effective temperature from our revised luminosity and radius. Our final results are $M_*=0.089 \pm 0.006 M_{\odot}$, $R_* = 0.121 \pm 0.003 R_{\odot}$, and $T_{\rm eff} =$ 2516 $\pm$ 41 K. Considering the degree to which TRAPPIST-1 system will be scrutinized in coming years, these revised and more precise stellar parameters should be considered when assessing the properties of TRAPPIST-1 planets. [less ▲]Detailed reference viewed: 87 (11 ULiège) Isotopic ratios in outbursting comet C/2015 ER61Yang, Bin; Hutsemekers, Damien ; Shinnaka, Yoshiharu et alE-print/Working paper (2017)Isotopic ratios in comets are critical to understanding the origin of cometary material and the physical and chemical conditions in the early solar nebula. Comet C/2015 ER61 (PANSTARRS) underwent an ... [more ▼]Isotopic ratios in comets are critical to understanding the origin of cometary material and the physical and chemical conditions in the early solar nebula. Comet C/2015 ER61 (PANSTARRS) underwent an outburst with a total brightness increase of 2 magnitudes on the night of 2017 April 4. The sharp increase in brightness offered a rare opportunity to measure the isotopic ratios of the light elements in the coma of this comet. We obtained two high-resolution spectra of C/2015 ER61 with UVES/VLT on the nights of 2017 April 13 and 17. At the time of our observations, the comet was fading gradually following the outburst. We measured the nitrogen and carbon isotopic ratios from the CN violet (0,0) band and found that $^{12}$C/$^{13}$C=100 $\pm$ 15, $^{14}$N/$^{15}$N=130 $\pm$ 15. In addition, we determined the $^{14}$N/$^{15}$N ratio from four pairs of NH$_2$ isotopolog lines and measured $^{14}$N/$^{15}$N=140 $\pm$ 28. The measured isotopic ratios of C/2015 ER61 do not deviate significantly from those of other comets. [less ▲]Detailed reference viewed: 9 (0 ULiège) L'astronomie dans le monde - 12/2017Manfroid, Jean Article for general public (2017)Première détection d’un anneau autour d’une planète naine - C/2017 K2 PANSTARRS – A/2017 U1 PANSTARRS – Étoile massive – Comète 96P/ Machholz – Voie lactée – GW170817 – Proxima du Centaure – A1689B11 – ... [more ▼]Première détection d’un anneau autour d’une planète naine - C/2017 K2 PANSTARRS – A/2017 U1 PANSTARRS – Étoile massive – Comète 96P/ Machholz – Voie lactée – GW170817 – Proxima du Centaure – A1689B11 – Matière noire [less ▲]Detailed reference viewed: 9 (0 ULiège) Joyaux cosmiques - 12/2017Manfroid, Jean Article for general public (2017)NGC 4874 – Arp 243 – Nébuleuse en nid d’abeilles – NGC 5398 – NGC 1316 - Astéroïdes dans Abell 370 – NGC 6753Detailed reference viewed: 11 (1 ULiège) L'astronomie dans le monde - 11/2017Manfroid, Jean Article for general public (2017)Géographie de Pluton – Qui nous observe ? – Pulsar binaire record – Rayons cosmiques énergétiques – Ondes gravitationnelles – U Antliae – 40 Eridani BC – L’astéroïde 2006 VW139/288P – Fréon cosmique – ... [more ▼]Géographie de Pluton – Qui nous observe ? – Pulsar binaire record – Rayons cosmiques énergétiques – Ondes gravitationnelles – U Antliae – 40 Eridani BC – L’astéroïde 2006 VW139/288P – Fréon cosmique – Tempête de neige sur Mars ! – Oxyde de titane sur Wasp-19b – La matière organique des comètes – Chondrites carbonées [less ▲]Detailed reference viewed: 7 (0 ULiège) Cassini, fin de mission - 11/2017Manfroid, Jean Article for general public (2017)Detailed reference viewed: 11 (0 ULiège) Joyaux cosmiques - 11/2017Manfroid, Jean Article for general public (2017)La nébuleuse Saturne, NGC 7009 – Vera Rubin RidgeDetailed reference viewed: 8 (0 ULiège) Les observateurs - 11/2017Demoulin, Ph Ponsard; Manfroid, Jean Article for general public (2017)L’éclipse solaire du 21 août – Achats intéressants – Sublime spectacle de fin de nuit - RapprochementsDetailed reference viewed: 10 (0 ULiège) Isotopic Ratios in a Peculiar Outbursting CometYang, Bin; Hutsemekers, Damien ; Shinnaka, Yoshiharu et alin Bulletin of the American Astronomical Society (2017, October 01), 49Isotopic ratios in comets provide keys for the understanding of the origin of cometary material, and the physical and chemical conditions in the early Solar Nebula. A newly discovered peculiar comet, C ... [more ▼]Isotopic ratios in comets provide keys for the understanding of the origin of cometary material, and the physical and chemical conditions in the early Solar Nebula. A newly discovered peculiar comet, C/2015 ER61, underwent an outburst with a total brightness increase of 2 magnitudes on the night of April 4th, 2017. The sharp increase in brightness offers a rare opportunity to measure the isotopic ratios of the light elements of this comet. We obtained two high-resolution spectra of C/2015 ER61 with UVES on Apr. 13 and Apr. 17 respectively. At the time of our observations, the comet was fading gradually since the outburst. We measured the 12C/13C and 14N/15N isotopic ratios from the CN Violet (0,0) band. In addition, we determined the 14N/15N ratio in NH2 for C/2015 ER61 from four pairs of NH2 isotopologue lines. Some 18OH lines were detected but the S/N of these lines is too low to derive a reliable 18O/16O estimate. We will present our UVES spectra of C/2015 ER61, obtained shortly after the outburst. We will also present the comparison of the Isotopic ratios of C/2015 ER61 with those of other comets. [less ▲]Detailed reference viewed: 20 (2 ULiège) The Structure of Chariklo’s Rings from Stellar OccultationsBérard, D.; Sicardy, B.; Camargo, J. I. B. et alin Astronomical Journal (The) (2017), 154Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned ... [more ▼]Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned observations of several occultations by Chariklo’s system in order to better characterize the physical properties of the ring and main body. Here, we use 12 successful occulations by Chariklo observed between 2014 and 2016. They provide ring profiles (physical width, opacity, edge structure) and constraints on the radii and pole position. Our new observations are currently consistent with the circular ring solution and pole position, to within the ±3.3 km formal uncertainty for the ring radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal significant width variations from ∼5 to 7.5 km. The width of the fainter ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and outer edges of C1R are consistent with infinitely sharp boundaries, with typical upper limits of one kilometer for the transition zone between the ring and empty space. No constraint on the sharpness of C2R’s edges is available. A 1σ upper limit of ∼20 m is derived for the equivalent width of narrow (physical width < 4 km) rings up to distances of 12,000 km, counted in the ring plane. [less ▲]Detailed reference viewed: 23 (3 ULiège) L'astronomie dans le monde - 10/2017Manfroid, Jean Article for general public (2017)Antarès – Bételgeuse – FRB à répétitions – Galaxies méduses – Les Pléiades – Méthylidyne – Nova Scorpii 1437 – Passages rapprochés – Cirrus martiensDetailed reference viewed: 5 (0 ULiège) Joyaux cosmiques - 10/2017Manfroid, Jean Article for general public (2017)NGC 7479 – Green Flash – Barnard 175 – NGC 7098Detailed reference viewed: 8 (1 ULiège) Monitoring of comets activity and composition with the TRAPPIST-North TelescopeMoulane, Youssef ; Jehin, Emmanuel ; Pozuelos Romero, Francisco José et alPoster (2017, September 19)Detailed reference viewed: 10 (2 ULiège) Early results for 41P/Tuttle­Giacobini­Kresak during its last incursion in the inner Solar System based on TRAPPIST telescope network observationsPozuelos Romero, Francisco José ; Jehin, Emmanuel ; Moulane, Youssef et alPoster (2017, September 19)Detailed reference viewed: 15 (4 ULiège) L'astronomie dans le monde - 09/2017Manfroid, Jean Article for general public (2017)Dark Energy Survey - SN1987A - Phobos - ELT, première pierre - Optique adaptative à l’ESO - Orion - Isocyanate de méthyle - 2014 MU69 - Tempête sur Neptune - Soleil - Une nouvelle détection pour LIGODetailed reference viewed: 11 (0 ULiège) Joyaux cosmiques - 09/2017Manfroid, Jean Article for general public (2017)SDSS J1110+6459 - Messier 77 - M16, M17, Sh 2-54 - Galaxies ultra-brillantesDetailed reference viewed: 7 (0 ULiège) Ground-based monitoring of comet 67P/Churyumov–Gerasimenko gas activity throughout the Rosetta missionOpitom, C.; Snodgrass, C.; Fitzsimmons, A. et alin Monthly Notices of the Royal Astronomical Society (2017), 469Simultaneously to the ESA Rosetta mission, a world-wide ground-based campaign provided measurements of the large scale activity of comet 67P/Churyumov-Gerasimenko through measurement of optically active ... [more ▼]Simultaneously to the ESA Rosetta mission, a world-wide ground-based campaign provided measurements of the large scale activity of comet 67P/Churyumov-Gerasimenko through measurement of optically active gas species and imaging of the overall dust coma. We present more than 2 yr of observations performed with the FORS2 low-resolution spectrograph at the VLT, TRAPPIST and ACAM at the WHT. We focus on the evolution of the CN production as a tracer of the comet activity. We find that it is asymmetric with respect to perihelion and different from that of the dust. The CN emission is detected for the first time at 1.34 au pre-perihelion and production rates then increase steeply to peak about 2 weeks after perihelion at (1.00 ± 0.10) × 10[SUP]25[/SUP] molecules s[SUP]-1[/SUP], while the post-perihelion decrease is more shallow. The evolution of the comet activity is strongly influenced by seasonal effects with enhanced CN production when the Southern hemisphere is illuminated. [less ▲]Detailed reference viewed: 36 (4 ULiège) Joyaux cosmiques - 06/2017Manfroid, Jean Article for general public (2017)SMC – Abell 370Detailed reference viewed: 6 (0 ULiège)