Energetic Outflows, Winds and Jets around Young Stars

Abstract

During the last decade the development of millimeter-wave and infrared astronomical spectroscopy has enabled astronomers to explore and directly probe the cold component of the galaxy, a component which contains 50–90% of the total mass of the interstellar medium and is rich in astrophysical complexity, activity and mystery. The result of this exploration has been a revolution in our understanding of star formation and the interstellar medium. Millimeter-wave CO observations, for example, led to the recognition of the giant molecular clouds (GMCs). With sizes often in excess of 100 parsecs and masses between 10⁵ and 10⁶ M_⊙, the GMCs are the largest and most massive structures in the Milky Way. Studies of these clouds have helped elucidate spiral structure in our galaxy and refined, through improvements in the rotation curve, the total mass of the Milky Way system (Blitz 1979, Bok 1983). Moreover, infrared observations have shown GMCs to be the primary sites of star birth in our galaxy. Indeed, molecular-line observations of these clouds have given us the first detailed glimpses into the physical processes associated with the earliest stages of stellar evolution and perhaps star formation itself.