Agenda de Lagrange

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Janvier 2018

Séminaire Lagrange
TBD
 mardi 23 janvier 2018, NEF - Mont Gros - CION - talk in French with slides in English - retransmis à Valrose
Eric LAGADEC - OCA/Lagrange
TBD.
Séminaire Lagrange
Observing the Moon: A large-scale hypervelocity impact laboratory
 mardi 30 janvier 2018, 10h30, NEF - Mont Gros - CION - talk in english - retransmis à Valrose
Chrysa Avdellidou (ESA/ESTEC)
When small pieces of space rock hit the lunar surface at high speeds, they produce flashes of light detectable from the Earth. Now, we have measured their temperature for the first
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    time, using a telescope facility funded by the European Space Agency (ESA). The new observations are helping us to find out more about the near-Earth space objects (NEOs) that cause them. In parallel, on-going hypervelocity experiments in small scales, will help to couple the observations and get insight into the impact process itself on regolith material.

Février 2018

Séminaire Lagrange
Fundamental gain in high-contrast imaging with the LBTI in Fizeau mode
 mardi 6 février 2018, 10h30, Valrose - Salle O. Chesneau - talk in English - retransmis au Mont Gros (salle tbc)
Fabien PATRU - LESIA
We show by numerical simulations a fundamental gain in contrast when combining coherently monochromatic light from two AO telescopes instead of using a single stand-alone AO telescope, assuming efficient control and
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    acquisition systems at high speed. A contrast gain map is defined as the normalized PSFs ratio of a single LBT aperture over the dual LBTI aperture in Fizeau mode. The global gain averaged across the AO-corrected field of view is improved by a factor of 2 in contrast in long exposures and by a factor of 10 in contrast in short exposures. The fringed speckle halo in short exposures contains not only high angular resolution information, as stated by speckle imaging and speckle interferometry, but also high-contrast imaging information. Compared to a single 8-m LBT aperture, the 23-m LBTI Fizeau imager can provide a gain in sensitivity (by a factor of 4), a gain in angular resolution (by a factor of 3) and, as well, a gain in raw contrast (by a factor of 2–1000 varying over the AO-corrected field of view). Despite opto-dynamical aberrations due to AO and piston control errors, such results suggest that the LBTI would already improve the contrast at near- and mid-infrared wavelengths (Patru et al. 2017a, 2017b, MNRAS).
Séminaire
Sulphur & Zinc in the Sculptor dwarf spheroidal galaxy
 lundi 12 février 2018, 11h00, PHC - Mont Gros - talk in English - retransmis à Valrose (Salle M. Dugué)
Asa SKULADOTTIR - MPIA
The Sculptor dwarf spheroidal galaxy is a Milky Way satellite with predominantly old stellar population, and is therefore an ideal target to study early chemical evolution. The chemical abundances of photospheres
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    of stars reveal the composition of their birth environment; studying stars of different ages, therefore, provides insight into the chemical enrichment history of the galaxy in which they dwell. For the first time, the elements S and Zn were measured in a large sample of stars in a stellar system other than the Milky Way. These chemical abundances in Sculptor show a significantly different behaviour from the Milky Way disk and halo; in particular a spread and very low values of [Zn/Fe]. These elements, S and Zn, are of special interest, since they are volatile and not depleted onto dust in interstellar gas. They can therefore be used for direct comparison with abundances in absorption systems ob served at high redshifts.
Séminaire Lagrange
From Lagrange to Arnold: more than two centuries of interaction between fluid mechanics and differential geometry
 mardi 13 février 2018, 10h30, NEF - Mont Gros - CION - talk in French with slides in English - retransmis à Valrose
Gerard GRIMBERG - Universite Federale de Rio
Differential geometry (DG), the study of differential forms and of manifolds, has become an essential tool in General Relativity, whose usage goes back about one century. Actually, differential geometry, sometimes under
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    a different name, has been in use for over two hundred years in fluid mechanics, and later in magnetohydrodynamics. The key figures of this talk will be * Lagrange, with his 1781 DG derivation of the condition satisfied by steady-state two-dimensional flow, * Helmholtz, with his 1858 vorticity flux invariance, an early instance of Lie invariants, * Clebsch, with his 1859 introduction of what is now called Clebsch variables, that makes use of variational tools introduced by Jacobi, * Hankel, with his 1861 derivation of what would later be called Kelvin's circulation invariant from Cauchy's 1815 invariants (Hankel was strongly stimulated by Riemann and such integral invariants were actually precursors of Poincare invariants), * Synge (1937) and Lichnerowicz (1941), with their use of Cartan’s integral invariants for relativistic hydrodynamics, * Arnold, with his 1966 infinite-dimensional DG variational formulation of incompressible Euler flow, * Ebin and Marsden, with their 1970 discovery that Lagrangian-coordinates formulations do not 'lose spatial derivatives', which throws much light on the issue of Lagrangian temporal analyticity first studied by Serfati (1995).
Séminaire Lagrange
tba
 mardi 20 février 2018, 10h30, NEF - Mont Gros - CION - talk in english - retransmis à Valrose
Roxanne Ligi - INAF

Mars 2018

Séminaire Lagrange
TBD
 mardi 13 mars 2018, 10h30, O. Chesneau, Valrose - talk in English - retransmis au Mont Gros, salle Perrotin (tbc)
Frans SNIK - Leiden University
Séminaire Lagrange
Dynamique atmosphérique des exoplanètes
 mardi 20 mars 2018, NEF - Mont Gros - CION - talk in French with slides in English - retransmis à Valrose
Vivien PARMENTIER - Laboiratoire d'Astrophysique de Marseille
TBD.
Séminaire Lagrange
tba
 mardi 27 mars 2018, 10h30, Salle Henon - PHC - Mont-gros - talk in english - retransmis à Valrose
Nadine Neumayer - MPIA

Avril 2018

Séminaire Lagrange
TRAPPIST & M-dwarf planets
 mardi 3 avril 2018, 10h30, NEF - Mont Gros - CION - talk in French with slides in English - retransmis à Valrose
Michael GILLON - Université de Liège

Mai 2018

Séminaire Lagrange
Outflow Activity in the Sub-Stellar Mass Regime
 mardi 29 mai 2018, 10h30, NEF - Mont Gros - CION - talk in French with slides in English - retransmis à Valrose
Emma WHELAN - Maynooth University, Rep. of Ireland

Juin 2018

Séminaire
tbd
 mardi 5 juin 2018, 10h30, NEF - Mont Gros - CION - talk in english - retransmis à Valrose
Hans-Martin SCHMID - ETH Zurich
      

Mise à jour : 17/01/18 08:48