Observations of Protobinary Systems

Abstract

High resolution images at millimeter wavelengths are providing new insights into the formation of binary and multiple star systems. These wavelengths are particularly useful in studying the earliest stages of multiplicity because they trace the bulk material distribution in the circumstellar environment and can penetrate 1000's of magnitudes of visual extinction. Current millimeter wavelength observations are finding a high incidence of multiplicity among young systems and that multiplicity begins at birth, or before. While the statistics are poor, the types of systems found (independent envelope, common envelope, and common disk systems) follow theoretical ideas about binary and multiple star formation. Systems can be identified which exhibit the characteristics of prompt initial collapse, central fragmentation during collapse, and fragmentation in high angular momentum scenarios. Expansion of this work to more systems and to more detailed studies of the structure and kinematics of individual systems will provide valuable insights into the formation of multiple systems.