Massive stars and their interaction with the interstellar medium

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The life of massive stars is a troubled one: over their lifetime, they lose a significant fraction of their mass via strong winds and, when they die in a final catastrophic supernova explosion, they eject yet more mass, sometimes giving off all that was left before the explosion.  By doing so, they seed the interstellar medium with elements which were fabricated in their interiors and which are later incorporated in new generations of stars and planets.  Many of the elements which make up our body were in fact fabricated in these stars eons ago. More significant though is the impact these strong winds and supernova explosions have on the surrounding interstellar medium.  It is this interaction between stellar winds and supernova remnants, on one hand, and the interstellar medium on the other hand, which is the subject of this study.  The shocks which sweep the interstellar medium following these violent events excite the surrounding gas which in turn emit radiation which can be picked up by telescopes on Earth.  The Synthesis Telescope of the Dominion Radio Astrophysical Observatory (National Research Council) in Penticton, B.C., has been carrying out a survey of the plane of our Galaxy, the Milky Way, and these observations, known as the Canadian Galactic Plane Survey (CGPS), play a crucial role in the proposed research. The ultimate aim is to better understand the physical processes which excite the gas, to assess to what extent the life of the star prior to its supernova explosion has affected the surrounding medium and how the latter itself affects the further expansion of the supernova remnant. This project involves studying individual objects, often identifiable by their shell-like forms or by the presence of known massive stars, as well as analyzing how these winds and supernova explosions collectively shape our Milky Way, triggering in some cases second-generation star formation and giving the surrounding Milky Way gas large expanding motions.