Archives Séminaires 2019-2020

Séminaire

Séminaire IPAG de Tomas Stolker (ETH Zurich), jeudi 14 novembre 2019 à 11h00, IPAG seminar room

We have entered an exciting era in which high-resolution instruments provide detailed insight into the formation, orbital architectures, and atmospheric characteristics of directly imaged planets and brown dwarfs. Along the spectral sequence towards later type objects, atmospheres emit the majority of their photons at mid-infrared wavelengths beyond 3 micron, a regime which is expected to provide complementary information about the atmosphere’s chemical abundances and cloud configuration. We (…)

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Séminaire IPAG de Jean-François Robitaille (IPAG), jeudi 21 novembre 2019 à 11h00, IPAG seminar room

Understanding the physics of the star formation process in molecular clouds is one of the most fundamental ambitions of modern astrophysics. Through these physical processes the interstellar gas phase changes, forming dense coherent structures. Historically, most research in this area was focused on two strategies : describing the local peaks of emission associated with the filamentary structures or the star-forming cores, or analysing statistically the global gas distribution of (…)

Séminaire exceptionnel

Séminaire IPAG de Giorgio Matt (Univ. Roma Tre), lundi 25 novembre 2019 à 14h30, IPAG seminar room

IXPE, the Imaging X-ray Polarimetry Explorer, has been selected by NASA as the next mission in the Small Explorer Program, for a launch in early 2021. IXPE, a collaboration between NASA and ASI (the Italian Space Agency), will reopen, after a gap of more than 40 years, the X-ray polarimetric observing window.
In this seminar, the main characteristics of the mission and its scientific objectives will be described. While at present only one positive measurement, dating back to the 70s, is (…)

Séminaire

Séminaire IPAG de Claire Davies (University of Exeter), jeudi 28 novembre 2019 à 11h00, IPAG seminar room

Direct observations of the innermost au of protoplanetary discs allow us to probe the inner disc structure and its impact on the bulk disc structural evolution (one potential product of which is the formation of planetary systems). For the closest young stellar objects (YSOs), the inner disc regions subtend an angle on the order of 10s of milliarcseconds at most - a distance scale only accessible to optical long baseline interferometry.
In the first section of my talk, I will focus on (…)

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Séminaire IPAG de Sébastien Guillot (IRAP), jeudi 5 décembre 2019 à 11h00, IPAG seminar room

The Neutron Star Interior Composition Explorer (NICER) has been in operation from the International Space Station since June 2017. Its primary science goals is to measure the radius and mass of millisecond pulsars, fast-spinning X-ray emitting neutron stars.
To achieve this, a handful of these pulsars have been observed by NICER, totalling more than 1 Megaseconds each. By accurately modelling their phase-energy resolved light curves, originating from their hot polar caps, one can obtain (…)

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Séminaire IPAG de Pierre Beck (IPAG), jeudi 12 décembre 2019 à 11h00, IPAG seminar room

Comets and most asteroids are extremely dark objets. They typically reflect only a few percent of the incoming light.
I will discuss the nature of dark Solar System small bodies based on ground-based observations, in situ observation (i.e. VIRTIS / ROSETTA) and laboratory measurements.
I will discuss in particular the case of C-type near-Earth asteroids, which are being targetted by two sample-return missions and how they might (or not) be representative of the main-belt population. (…)

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Séminaire IPAG de Allison Man (University Toronto), jeudi 9 janvier 2020 à 11h00, IRAM seminar room

A fundamental question in galaxy evolution is how galaxies acquire diverse colours and morphologies. The current paradigm suggests that massive galaxies experienced accelerated growth in the early Universe and eventually quench their star formation. Exactly how galaxies quench is not well-understood. Many mechanisms have been proposed in the literature, yet a definite conclusion remains elusive. I will present an overview of the current state of the art and discuss future perspectives on (…)

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Séminaire IPAG de David Ehrenreich (Genève), jeudi 16 janvier 2020 à 11h00, IPAG seminar room

Exoplanets are often found at short distances from their host stars. There, they represent unique laboratories to study highly-irradiated atmospheres with exotic chemistry and extreme climates. Finding out about the atmospheric composition and dynamical processes can in turn help us understanding the evolution of these objects. One such process is atmospheric escape, which is now surmised to have sculpted whole populations of planets. Enormous progress in detecting exoplanet mass-loss and (…)

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Séminaire IPAG de M.-A. Miville-Deschenes (CEA Saclay), jeudi 23 janvier 2020 à 11h00, IPAG seminar room

Today we do not understand fundamental aspects of the formation of collapsed structures in the Universe. How the injection of energy, mass, and metals from stars and galaxies play against the forces of cooling, condensation, turbulence, magnetic fields, and gravity to establish the Universe we see, remains an open question in even the broadest of strokes. The interstellar medium (ISM), the reservoir from which every star is formed, is the laboratory where the complex multi-scale and (…)

Séminaire IPAG de Basile Augé (IPAG), jeudi 30 janvier 2020, 11h00, IPAG seminar room

Based in Caen (Normandy), the large national heavy-ion accelerator (GANIL – Grand Accélérateur National d’Ions Lourds) can produce and accelerate beams from carbon to uranium up to 100 MeV / nucleon energies. These ions are used by many experimenters covering a wide variety of research fields : nuclear physics, material physics, medical physics, nuclear astrophysics, astrochemistry...
I will present various experiments which have been, are or will be carried out in these disciplines with a (…)