Archives Séminaires 2016-2017

Séminaire

Séminaire IPAG de Silvère Gousset (IPAG), jeudi 15 décembre 2016 à 11h00, salle Manuel Forestini IPAG

The NanoCarb instrument concept is a joint innovation from both Grenoble University and ONERA. Based on a compact Fourier Transform spectrometer, the instrument design is easily adaptable for a large field of on-board applications, from flying hyperspectral sensor on drone to miniaturized nanosatellite mission. The presented study demonstrates the spectrometer’s capacity to measure the CO2 and CH4 concentrations on Earth from a nanosatellite with respective sensitivities of 1ppm and 32ppb (…)

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Séminaire IPAG de Miguel Montarges (IRAM), jeudi 19 janvier 2017 à 11h00, IRAM seminar room

Evolved stars are the main contributors to the chemical enrichment of the interstellar medium. Nuclear fusion creates heavy elements in their core that are transported up to the photosphere where they are expelled through an important mass loss. As material moves away from the star it is cooling and becoming more complex. Several processes behind this mass loss remain poorly understood.
I will review my recent results in observing the photosphere and the close circumstellar environment of (…)

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Séminaire IPAG de Hélène Courtois (IPNL, Université de Lyon I), jeudi 26 janvier 2017 à 11h00, IRAM seminar room

I will present the evolution of the “Cosmic Flows” program spanning ten years of research since its inception in 2006. From CF1 to the latest CF3 data-set, an order of magnitude in the number of observational galaxy distances is gained, meanwhile the cosmographied volume is multiplied by 150. A theoretical framework has been developed so as to accommodate and analyze the data. This includes the Bayesian reconstruction tools of the Wiener filter and constrained realizations, constrained (…)

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Séminaire IPAG de Pierre-Yves Longaretti (IPAG), jeudi 2 février 2017 à 11h00, IPAG seminar room

Disks are among the most common and most studied objects in astrophysics. At first sight, all disks are superficially similar, as the central object dominates their gross geometric and physical characteristics. However, this apparent uniformity is lost at a closer look. Astrophysical disks differ considerably in their microphysical and thermodynamic properties, and a host of weaker dynamical effects provide for a wide spectrum of dynamical phenomena and control their long term evolution. (…)

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Séminaire IPAG de Vincent Bourrier (Observatoire de Genève), jeudi 16 février 2017 à 11h00, IPAG seminar room

Observations of exoplanets during the transit of their host star allow us to probe the structure and composition of their atmospheres. While visible and infrared wavelengths give access to low altitudes in the planetary atmosphere, space-borne ultraviolet observations can reveal the highest atmospheric layers. Transit observations of strongly irradiated gaseous giants led to the detection of ‘evaporation’, when massive amounts of gas escape from the planet and form an extended exosphere (…)

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Séminaire IPAG de Olivier Poch (CSH, University of Bern), jeudi 9 mars 2017 à 11h00, IPAG seminar room

I will present my activities relative to the questions of the detection, the evolution, and the role of organic molecules at the surfaces of planets, comets and icy satellites. I will describe experimental laboratory simulations, performed with analogues of astrophysical surfaces, whose results support space missions (MSL, Rosetta) and astronomical observations (SPHERE). I will describe sublimation experiments of analogues of cometary ices, showing how organic molecules can influence the (…)

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Séminaire IPAG de Astrid Lamberts (Caltech), jeudi 16 mars 2017 à 11h00, IPAG seminar room

Massive stars are key ingredients to galaxy evolution, through their powerful flux, winds and final explosions. The resulting compact objects are extreme systems, capable of accelerating matter up to relativistic speeds, leading to very high energy emission. Eventually, their mergers can result in the recently detected gravitational waves. In this talk I will present snapshots of the lifecycle of massive binaries based on high resolution numerical simulations. The latter reveal the structure (…)

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Séminaire IPAG de Sylvain Douté (IPAG), jeudi 23 mars 2017 à 11h00, IPAG seminar room

On Mars CO2 is a major component of the atmosphere whether in the gaseous state (abundance of 95%) or in the solid state forming clouds at high altitudes. During winter, up to 30 % of the atmospheric CO2 condenses or precipitates at the surface to form seasonal polar deposits. They completely sublimate in spring, except in the South pole where a residual cap persists during summer. Recent studies have shown that the sublimation of these condensates causes the erosion of their substratum, the (…)

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Séminaire IPAG de Jérémie Lasue (IRAP), jeudi 30 mars 2017 à 11h00, IPAG seminar room

Since its landing in August 2012, the Mars Science Laboratory (Curiosity) rover has just completed two full martian years (approximately 4 terrestrial years) of exploring Gale Crater on the surface of Mars. As of October 2014, the rover started its goal to study layered sediments in the central mound of the crater. Before that, the mission drove and studied several areas on its way to the central Mound. Along the way, the rover observed evidence for past liquid water at the surface in the (…)

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Séminaire IPAG de Michael Ireland (Australian National University), jeudi 6 avril 2017 à 11h00, IPAG seminar room

Imaging the process of giant planet formation in the nearest young associations is just at the edge of possibility with 8-10m class telescopes. Empirical evidence is mounting that giant planets with separations from their host star wider than that of Jupiter are relatively rare. At a 5 AU separation (0.035 arcsec), a young Jupiter is barely resolved from its host star on 8-10m class telescopes, but is well resolved by an ELT. I will describe the fundamental limits of non-coronagraphic (…)