  Mass is constantly being recycled in the universe. One of the most powerful
recycling paths is via stellar mass-loss. All stars exhibit mass loss with
rates ranging from ~10(-14) to 10(-4) M(sun) yr-1, depending on spectral type,
luminosity class, rotation rate, companion proximity, and evolutionary stage.
The first generation of stars consisted mostly of hydrogen and helium. These
shed material - via massive winds, planetary nebulae and supernova explosions -
seeding the interstellar medium with heavier elements. Subsequent generations
of stars incorporated this material, changing how stars burn and providing
material for planet formation. An understanding of mass loss is critical for
modeling individual stars as well as answering larger astrophysical questions.
Understanding mass loss is essential for following the evolution of single
stars, binaries, star clusters, and galaxies. Mass loss is one of our weakest
areas in the modeling of fundamental stellar processes. In large part this is
owing to lack of confrontation with detailed observations of stellar
photospheres and the mass-loss process. High resolution optical imagery with
telescope arrays is beginning to provide these data and, combined with
spectroscopy and broad infrared and sub-mm coverage, supporting more
sophisticated models on fast computers and promising a new era in mass-loss
studies.
