Nebulae A University of Chicago astronomer has for the first time determined the shapes of newly formed shells of dying stars. This experiment may shed some light on that process. Optical spectropolarimetry had never before been used to study these dying stars.
Planetary nebulae are the end stage of the evolution of stars such as our sun.
What puzzles astronomers is that the shapes of these outer shells can vary from spherical to highly asymmetric. Clues as to why planetary nebulae adopt these different shapes may lie in the stars that created them, or in the factors that influenced their evolution. Theory suggests that the shapes are determined very early in the formation of a planetary nebula, but, unfortunately, there is little observational evidence to support this claim. We don't understand the early evolution of the planetaries or how the early mass loss shapes their later evolution. Trammell and her colleagues sought to learn more about the evolutionary process by studying stars that were on the verge of becoming planetary nebula.