Archives Séminaires 2018

Optical Interferometry of a Microquasar : Resolving Super-Eddington Outflows in SS 433

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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Characterization by HPLC-HRMS of biological molecules in complex organic materials of interest for planetology

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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Some things special about NEAs : Geometric and environmental effects on the optical signatures of hydration

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 meteorites, (...)

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Escape of ionizing radiation from galaxies

Séminaire IPAG de Ivana Orlitova (IPAG & Astronomical Institute of the Czech Academy of Sciences), jeudi 6 septembre 2018 à 11h00, salle Manuel Forestini

Reionization of the universe in the first billion years of its history represented a major change. However, the sources that caused it are still being debated. Quasars may have been too rare in that epoch, while star-forming galaxies face the problem of inefficient ionizing radiation escape : the fraction that can escape into the intergalactic medium depends on the structure of the interstellar medium. I will present a rare class of nearby star-forming galaxies, known as green peas, which (...)

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