date: 2011 May 18 (Wed) 15:00-16:00
room: Kobe University, Science and Technology Research Building #4-809
speaker: Itsuki Sakon (The University of Tokyo)
organizer: Hiroshi Kimura
title: Observing the Sites of Dust Formation in Circumstellar Environments
abstract: The process of dust condensation in the gas ejected from stars of various spectral types during their evolution shall be an important issue to be demonstrated observationally. While the intermediate- to low-mass stars are generally expected to play significant roles as the dust budgets in the Milky Way and in the present universe, massive stars may contribute efficiently towards the chemical enrichment in the early universe by providing heavy atoms synthesized during their stellar evolution and supplying dust grains into the circumstellar space via the stellar mass-loss activities and the supernova explosions. However, we have quite a limited knowledge on the compositions and the amount of dust produced around each type of stars, particularly, from the observational point of view.
We have carried out the multi-epoch mid-infrared observations of periodically dust-forming Wolf-Rayet binaries and dust forming novae taking advantages of the high-spatial resolution capabilities achieved by mid-infrared instruments onboard 8m class ground-based telescopes, aiming to directly demonstrate the sites of dust nucleation in the stellar ejecta. In this presentation, the sites of dust nucleation and the following chemical evolution and/or destruction in the circumstellar environments are discussed based on those mid-infrared imaging and spectroscopic datasets collected so far.