Archives Séminaires 2018-2019

Séminaire

Séminaire IPAG de Didier Fraix-Burnet (IPAG), jeudi 4 avril 2019 à 11h00, salle Manuel Forestini

Dealing with large amount of data is a new problematic task in astrophysics. One may distinguish the management of these data (astroinformatics) and their scientific use (astrostatistics) even if the border is rather fuzzy. Dimensionality reduction in both the number of observations and the number of variables (observables) is necessary for an easier physical understanding. This is the purpose of classification which has been traditionally eye-based and essentially still is but this (…)

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Séminaire IPAG de Maud Galametz (CEA Saclay), jeudi 28 mars 2019 à 11h00, salle Manuel Forestini

The interstellar dust is a key galaxy component and a strong diagnostic tool to trace the lifecycle of matter in the ISM. Herschel and Planck have revolutionised our understanding of dust properties in our own Galaxy and nearby galaxies. Recent observations and comparisons of AV estimates from the dust with optical estimates in the Galaxy have highlighted the need of a new recalibration of our dust reservoirs. In this seminar, I will discuss how our knowledge of the dust composition has (…)

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Séminaire IPAG de Jacques Kluska (KU Leuven), jeudi 21 mars 2019 à 11h00, salle Manuel Forestini

Protoplanetary disks are a byproduct of star formation and are the birth places of future planetary systems. However, besides young stars there are other objects that are surrounded by very similar disks of dust and gas : the post-AGB binaries. Despite very different formation processes, the circumbinary disks around those evolved binaries have a similar infrared excess to disks around young stars, a Keplerian rotation profile and evidence of dust processing. Altogether, those similarities (…)

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Séminaire IPAG de Idel Waisberg (MPE Garching), jeudi 14 mars 2019 à 11h00, salle Manuel Forestini

GRAVITY@VLTI has allowed to spatially resolve outflow structures in X-ray binaries at sub-milliarcsecond resolution for the first time. The unique microquasar SS 433 harbors a hypercritical accretion disk that behaves as an accretion-powered massive star, converting its X-ray luminosity to longer wavelengths and turning it into a primarily "optical" object, making it the ideal X-ray binary target for optical interferometry. I will present GRAVITY spectro-interferometric observations of SS (…)

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Séminaire IPAG de Cédric Wolters (Doctorant IPAG), jeudi 7 mars 2019 à 11h30, salle Manuel Forestini

The origin of the complex molecules that lead to life on Earth is discussed around two different hypotheses : an exogenic source with comets and asteroids and an endogenic source with atmospheric hazes. The organic matter present in comets and asteroids formed very early in the history of the Solar System and subsequently evolved chemically by irradiation and by aqueous and thermal alteration. Atmospheric hazes are formed locally by the host star irradiation of the atmosphere. This process (…)

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Séminaire IPAG de Sandra Potin (Doctorante IPAG), jeudi 7 mars 2019 à 11h00, salle Manuel Forestini

Spectral signatures of hydration are detected on a majority of Main-Belt Asteroids (MBAs) corresponding to C-types asteroids, while they seem scarce in the Near-Earth Asteroids (NEAs) population. Two space missions are presently “en route” toward possibly volatile-rich near-Earth asteroids (NEAs) (Hayabusa-2 and Osiris-REX) and the origin of this hydration difference remains to be understood. Signatures of aqueous alteration are also recorded in the optical properties of primitive (…)

Séminaire spécial (Cancelled)

Séminaire IPAG de Michel Blanc (IRAP), jeudi 14 février 2019 à 14h00, salle Manuel Forestini

La Chine est aujourd’hui le pays qui réalise le plus grand nombre de lancements de satellites par an, et le second producteur mondial d’article scientifiques. Ses ambitions dans le domaine des sciences et des technologies, qu’elle considère comme un moteur de son développement, se concrétisent d’année en année. Le secteur scientifique spatial en est une vitrine très visible, et offre des opportunités d’expériences embarquées de plus en plus nombreuses, tout d’abord pour sa propre communauté (…)

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Séminaire IPAG de Bailey Tetarenko (University of Michigan), jeudi 14 février 2019 à 11h00, salle Manuel Forestini

From how planets and newborn stars form to the evolution of entire galaxies, many astrophysical objects grow and evolve by accumulating mass through a disc. However, currently our understanding of the detailed physics governing this process is fragmented due to the limits of theoretical work and missing observational constraints. The recurring outbursts associated with matter flowing onto compact stellar remnants (black holes, neutron stars, white dwarfs) in low-mass X-ray binary systems (…)

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Séminaire IPAG de Yann Boehler (IPAG), jeudi 7 février 2019 à 11h00, salle Manuel Forestini

During the last 2-5 years, the advent of new observational facilities such as the Atacama Large Millimeter Array (ALMA), or the Sphere instrument on the Very Large Telescope (VLT), has drastically changed our vision of protoplanetary disks. Thanks to their very high spatial resolution and sensitivity, these instruments have shown that protoplanetary disks are not homogeneous structures as hypothesized before, but present numerous structures in the dust emission : azimuthal asymmetries, (…)

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Séminaire IPAG de Gabriel Tobie (LPG Nantes), jeudi 31 janvier 2019 à 11h00, salle Manuel Forestini

The exploration of Jupiter’s and Saturn’s system respectively by Galileo (1996-2003) and Cassini-Huygens (2004-2017), has revealed that several moons around Jupiter (Europa, Ganymede, Callisto) and around Saturn (Titan, Enceladus, Mimas) harbor a subsurface salty ocean underneath their cold icy surface. By flying through the icy-vapor plume erupting from Enceladus’ south pole, Cassini proceeded for the first time to the analysis of fresh materials coming from an extraterrestrial ocean. These (…)