Archives Séminaires 2011-2012

Séminaire

Séminaire IPAG de John Monnier (U. of Michigan), jeudi 10 mai 2012 à 11h00, IPAG seminar room

Under even the best atmospheric conditions, telescope diffraction fundamentally limits the angular resolution for astronomical imaging. Using interferometry, we can coherently combine light from widely-separated telescopes to overcome the single-telescope diffraction limit to boost our imaging resolution by orders of magnitude. I will review recent technical and scientific breakthroughs made possible by the Michigan Infrared Combiner of the CHARA Array on Mt. Wilson, CA, with baselines of (...)

Séminaire exceptionnel

Séminaire IPAG de Bo Reipurth (U. of Hawaii), mercredi 23 mai 2012 à 11h00, IPAG seminar room

Newly born triple systems are inherently unstable, and undergo chaotic dynamic evolution until they find a stable configuration or they break apart. Detailed numerical simulations of three stellar embryos embedded in a cloud core map out the effects of dynamics and accretion. These two processes interact in complex ways, and I explore the main pathways that stellar embryos follow as they gain mass during the protostellar phase. The results lead to observational predictions, and I present (...)

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Séminaire IPAG de Alan Stern (Southwest Research Institute, San Antonio, Texas), jeudi 31 mai 2012 à 11h00, IPAG seminar room

In mid-2015, about 3 years from now, NASA’s New Horizons mission will culminate its journey across the inner and middle zones of the planetary system to reach Pluto. Beginning in January 2015 and extending until August 2015, New Horizons will explore this system. Aboard New Horizons are 7 scientific instruments including UV and IR mapping spectrometers, color and panchromatic imagers, a dust counter, two plasma instruments, and radio science. I will discuss the scientific objectives of the (...)

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Séminaire IPAG de Paul F. Goldsmith (JPL, Caltech), jeudi 14 juin 2012 à 11h00, IPAG seminar room

Models of the gas-phase chemistry in dense clouds predict molecular oxygen (O2) to be almost as abundant as carbon monoxide (CO). Searches for Galactic O2 carried out with the SWAS and Odin spacecraft have yielded upper limits on the abundance of molecular oxygen typically 2 orders of magnitude below those predicted by gas-phase models. A variety of explanations have been proposed to explain this low abundance. Some of these are based on depletion of atomic oxygen onto dust grains, (...)

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Séminaire IPAG de Aline Vidotto (U. of St Andrews) , jeudi 21 juin 2012 à 11h00, IPAG seminar room

The stellar winds of cool, main-sequence (boring) stars are very tenuous and persist during the star lifetime. Although they may not cause a fundamental impact in the evolutionary track of a star (opposed to winds of massive stars), they regulate the rotation of the star and can affect surrounding planets. Because these winds are incredibly tenuous, up to now, there have not been any direct measurements of their properties (except for the Sun itself). To determine the fundamental properties (...)

Séminaire

Séminaire IPAG de Tanuka Chattopadhyay (Calcutta University), jeudi 28 juin 2012 à 11h00, IPAG seminar room

Stellar Initial Mass Function (IMF) is an important aspect for delineating a clear picture of star formation scenario in a broad spectrum of environments — from star clusters, associations, field stars to much bigger ones like dwarf galaxies, giant galaxies, cluster of galaxies etc. A stochastic model has been developed for the hierarchical fragmentation of a molecular cloud. Here, the number of fragments, time between successive fragmentation steps, and mass of a fragment are considered as (...)