665 research outputs found
Classifications of elliptic fibrations of a singular K3 surface
No full textWe classify, up to automorphisms, the elliptic fibrations on the singular K3 whose transcendenatl lattice is isometric to +
3512. Lettres secrètes et curiales du pape Urbain V, publiées ou analysées par P. Lecacheux, Paris, 1902 (Bibliothèque des écoles françaises d'Athènes et de Rome)
No full text3512. Lettres secrètes et curiales du pape Urbain V, publiées ou analysées par P. Lecacheux, Paris, 1902 (Bibliothèque des écoles françaises d'Athènes et de Rome). In: Molinier Auguste. Les Sources de l'histoire de France - Des origines aux guerres d'Italie (1494). IV. Les Valois, 1328-1461. Paris : A. Picard et fils, 1904. p. 102
Lettres secrètes & curiales du Pope Urbain V (1362-1370) se rapportant à la France,
No full textVols. 3-4 lack subseries.Vol. 4: "Table de matières, par G. Mollat."Vol. 3-4 published: Paris, E. de Boccard.Vol. 3: "Extraites des registres d'Avignon et du Vatican par P. Lecacheux et G. Mollat."Mode of access: Internet
Jovian DAM “Arcs” and Auroral Context (abstract). Planetary Radio Emissions| PLANETARY RADIO EMISSIONS VII 7|
No full textWe compare a large database of Jovian DAM ‘great arcs” events with the most recent compilation of Io footprint (IFP) properties obtained from HST images of Jupiter UV auroras. The radio data was built from the last 16 years of Jupiter radio monitoring by the Wind/WAVES space experiment and by the Decameter array in Nan¸cay, and contents more than 3500 individual events. The analysis of this huge statistics lead to the following conclusions: ”Great arcs” can be found on spectrograms of both Io and non-Io controlled emissions (in nearly equal proportion), showing that the arc phenomenon is not specific to the particular Io-Jupiter interaction scenario. In the case of Io-controlled events, the observed arc curvatures and senses of circular polarisation, show that most of the observed events originate from one or several of the four possible high latitude limbs (corresponding to the well known A,B,C and D ‘regions” in CML-Io phase diagram). In each region, a close relationship exists, at a given frequency, between observer’s direction and Io’s orbital position at the time of the event; already reported as “DE effect”, it means a surprisingly tight beaming constraint. By using reference IFP ovals (Bonfond et al., JGR 114, 2009) and magnetic field model (VIP4), the emission angle can be estimated for each individual events. When counting from magnetic field direction at the source location, the distribution of emission angles is broadly centred on ~ 70?, as previously determined by many authors. The distribution gets narrowed when the magnetic field gradient is rather used, suggesting that the observed emission angle depends primarily on propagation conditions near the source. Because of the limited accuracy of available magnetic field models, it is unclear whether our estimate of a ~ 10? “lead angle” between the active radio field line footprint and the auroral IFP, can be considered as statistically significant or not
Direction Finding and Polarization Measurements of SKR (invited). Planetary Radio Emissions| PLANETARY RADIO EMISSIONS VII 7|
No full textThe Saturnian Kilometric Radio emission (SKR), discovered and briefly observed by Voyager spacecraft in 1980-81, is now studied in depth by Cassini, which is still in orbit around Saturn, since mid 2004. Aboard Cassini, the main radio astronomy system (the HFR part of the RPWS instrument) is based on digital, real time, spectral correlation of several pass band filters, analyzing multiple wire antennas. This system allows, in principle, the full second order statistics of the analyzed signal to be retrieved, thus providing, compared to a simple antenna system, some extra information on the received radio waves: mainly about the spatial brightness distribution (leading to direction finding (DF) for a point source model) and the intrinsic polarisation of the measured radio source. While there is no doubt that SKR, like terrestrial and Jovian radio emissions, is powered via a cyclotron maser (CMI) originating from accelerated auroral particles, the exact scenario remains, at the moment, far from being understood: the complex modulation of the SKR at the planetary spin rate is perplexing; the fact that the apparent SKR polarization changes with observer’s latitude and contains a substantial amount of linear polarisation when observed from mid to high latitudes, is quite unexpected and likely the indication of a complex source structure and/or unusual propagation regime in Saturn’s high latitude regions
4979 Otawara: flyby target of the Rosetta mission
No full textAn international observing campaign was organized to determine the physical and chemical characteristics of asteroid 4979 Otawara, which is the first target of the Rosetta mission (flyby on July 10, 2006). Knowledge of the physical parameters of the flyby targets is required for both refinement of the design of the spacecraft and the instrument payload, and optimization of the mission trajectory and scenarios. We present the results of observations obtained from December, 1998 through March, 1999. The spectral classification of 4979 Otawara could be either a pyroxene and/or olivine-rich S-type asteroid or a V-type asteroid, a member of the Vesta dynamical family. Further observations are needed in order to discriminate between the two spectral types. The synodic rotation period of Otawara is Psyn = 2.707 +/- 0.005 hr. The lower limit for the axial ratio of the enveloping ellipsoid is a/b >= 1.3. The circular effective radius is 2.0 or 1.3 km in the case of an S-type or a V-type asteroid, respectively. A lower limit on its density is obtained: rho min >= 1.9 g cm-3 if we assume that Otawara is an aggregate or rubble pile object. However, if Otawara is a single solid body, no constraint can be set on its density. 4979 Otawara is a small, fast rotating asteroid (FRA) and hence, will be a particularly interesting target to be studied from a spacecraft, since no fast rotator has been visited yet. partly based on observations carried out at the European Southern Observatory (ESO) of La Silla, Chile, and at Steward Observatory, University of Arizona, Tucson, AZ USA
Submillimetre observations of comets with Odin: 2001-2005
No full textThe Odin satellite, launched in February 2001, is equipped with a 1.1-m submillimetre telescope. Odin was used to observe the 557 GHz line of water with high spectral resolution in 12 comets between 2001 and 2005. Line shapes and spatial mapping provide information on the anisotropy of the outgassing and constraints on water excitation, enabling accurate measurements of the water production rate. Five comets were regularly observed over periods of more than one month to monitor the variation of their water outgassing rate with heliocentric distance. Observing campaigns have been generally coordinated with ground-based observations of molecular lines at Nançay, CSO or IRAM 30-m telescopes to obtain molecular abundances relative to water. Thanks to Odin's frequency coverage, it was also possible to detect the H 2 18O 548 GHz line, first in comet 153P/Ikeya-Zhang in April 2002 [Lecacheux, A., Biver, N., Crovisier, J. et al., 2003, Observations of water in comets with Odin. Astron. Astrophys. 402, L55-L58.] and then in comets C/2002 T7 (LINEAR), C/2001 Q4 (NEAT) and C/2004 Q2 (Machholz). The 16O/ 18O isotopic ratio (≈ 450) is consistent with the terrestrial value. Ammonia has been searched for in three comets through its J K = 1 0 - 0 0 line at 572 GHz and was tentatively detected in C/2001 Q4 and C/2002 T7. The derived abundances of NH 3 relative to water are 0.5% and 0.3%, respectively, similar to values obtained in other comets with different techniques. © 2006 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex
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