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November 2014
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Friday 7 November 2014 11:00-12:00 - Amphi

Abstract: TBD

Tim Morris (Durham) --- Adaptive Optics in the Land of the Giants

Friday 14 November 2014 11:00-12:00 - Amphi

Abstract: Astronomical observations made with the next generation of planned Extremely Large Telescopes hold immense potential to revolutionise our understanding of the Universe and our place within it. The scale of these optical monsters introduces problems that are not encountered on existing 8 to 10m class telescopes resulting in some form of Adaptive Optics (AO) being required to deliver even a seeing-limited focal plane. AO is not only key to optimising the light gathering power and delivering the high angular resolution images, but it also becomes fundamental to ELT operation. In this talk, I will highlight the worst of the potential effects that will be encountered when using an ELT (using the European ELT as an example), and then go on to describe how the current generation of on-sky AO demonstrators are being used to ensure that the ELTs can deliver science from (almost) day one. I will also present several results from the CANARY on-sky AO system, which was designed to demonstrate many of the untested AO modes that will be used at the E-ELT, including the very latest results showing the first ever Laser Tomographic AO (LTAO) corrected PSFs that were achieved earlier this year.

France Allard (ENS Lyon) --- Very Low Mass Stars, Brown Dwarfs and Gas Giant Exoplanets

Friday 21 November 2014 11:00-12:00 - Amphi

Abstract: Understanding the atmospheric and evolutive properties of brown dwarfs and gas giant exoplanets have been important challenges for modelers around the world since the discovery of the first brown dwarfs in the field (Nakajima et al. 1995) and in the Pleiades cluster (Rebolo et al. 1995). The early studies of brown dwarfs have provided rich insights into atmospheric physics, with discoveries ranging from cloud formation (Tsuji et al. 1996), methane bands (Oppenheimer et al. 1995) and ammonia bands formation (Delorme et al. 2008), to the formation of quasi-molecular KI-H2 absorption (Allard et al. 2007), and to disequilibrium chemistry (Yelle & Griffith 2001). New classical 1D models yield spectral energy distribution (SED) that match relatively well that of M dwarfs, brown dwarfs and young gas giant exoplanets despite these complexities. These models have for instance explained the spectral transition from M to L, T and now Y brown dwarf spectral types (Allard et al. 2013). However, in presence of surface inhomogeneities as revealed recently for a nearby brown dwarf (Crossfield et al. 2014), the SED may well fit exactly, but the model parameters could be far from exact, e.g. with the effective temperature by several hundred kelvins too cool in the case of dusty brown dwarfs and young gas giant exoplanets!

I will review the progress achieved in reproducing the spectral properties of very low mass stars, brown dwarfs/gas giant exoplanets, and review progress in modeling more accurately their atmospheres using Radiation HydroDynamical (RHD) simulations.

Matthieu Gounelle (un livre un auteur) --- Météorites - A La Recherche De Nos Origines

Friday 28 November 2014 11:00-12:00 - Amphi

Abstract: La probabilité n’est pas grande, mais elle existe : un jour, un bolide extraterrestre percutera la Terre. Est-ce là cependant tout ce que les météorites nous apprennent ? Matthieu Gounelle nous invite ici à réévaluer nos craintes et, à l’aune des dernières découvertes cosmo-chimiques et astrophysiques, à apprécier la richesse insoupçonnée des pierres tombées du ciel. D’où viennent-elles ?...

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