Archives Séminaires 2017-2018

Séminaire

Séminaire IPAG de Jason Dexter (MPE Garching), jeudi 14 juin 2018 à 11h00, salle Manuel Forestini IPAG

Two long baseline interferometry experiments operating at millimeter and near-infrared wavelengths provide an unprecedented look at accretion and outflows in the immediate vicinity of massive black holes. In the brightest quasars, the VLTI GRAVITY instrument can now be used to study the structure and dynamics of the broad emission line region in spectro-interferometry. In the Galactic center, GRAVITY and the global Event Horizon Telescope array resolve event horizon scales in both space and (...)

Séminaire

Séminaire IPAG de Omer Blaes (UCSB), jeudi 21 juin 2018 à 11h00, salle Manuel Forestini IPAG

AM CVn systems are extremely compact binary star systems consisting of a white dwarf that is accreting from a helium donor star. Interest in these systems arises primarily from the fact that they are sources of exotic classical novae and possibly even type Ia supernovae, as well as being detectable sources of gravitational waves by LISA. They are also amazing laboratories for exploring accretion disk physics. They exhibit all sorts of variability including broadband noise, superhumps, QPO’s, (...)

Séminaire

Séminaire IPAG de Attila Moor (Konkoloy Observatory), jeudi 28 juin 2018 à 11h00, salle Manuel Forestini IPAG

During their early evolution, newborn stars are surrounded by massive gas-rich circumstellar disks. According to the current paradigm, this primordial material dissipates by the age of 10 Myr in most systems, leaving behind a tenuous debris dust disk. The observable parts of these debris disks are composed of short-lived second generation dust grains that are replenished from collisional erosion of larger planetesimals. While the evolution of dust between the primordial and debris stages is (...)

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Séminaire IPAG de Virginie Faramaz (Jet Propulsion Laboratory), jeudi 5 juillet 2018 à 11h00, salle Manuel Forestini IPAG

Debris disks contain the solid remnants of planet formation that are in collisional cascade, and are proof that solid accretion has produced solids at least km-sized. It is thus not surprising that debris disks are sometimes accompanied by planets, which reveal themselves through their gravitational imprint on debris disks (sharp edges, apsidal alignment, warps…). For planets that are currently beyond reach of detection of our instruments and facilities, that is, planets in mature systems (...)

Séminaire

Séminaire IPAG de Emmanuel Jacquet (Muséum national d’Histoire naturelle), jeudi 12 juillet 2018 à 11h00, salle Manuel Forestini IPAG

Primitive meteorites, or chondrites, are witnesses of the first millions of years of the solar system, when the proto-Sun was surrounded by a dusty gas disc. Several varieties of them are known but it remains controversial what relative time/place of accretion they represent and what fractionation mechanisms imparted their deviation from a solar composition. Chondrites are dominated by millimeter-size igneous spheroids called chondrules, whose formation context likewise remains an opaque (...)