Stellar Shape-Shifters

Planetary nebulae form when a wind from a dying star blows away its outer layers, enveloping the star in a cloud of debris that can span many light years across. Often planetary nebulae have spectacularly complex shapes, leading to whimsical nicknames such as "Eskimo" or "Cat's Eye". However, the origin of these diverse shapes has been a long-standing puzzle; if the progenitor stars are spherical and lose mass uniformly in all directions, what sculpts their ejecta into these varied forms? Using observations of circumstellar radio waves, scientists are discovering that part of the answer is that the outflows from some dying stars are far more complex than once believed. This podcast explores how two types of radio wavelength observations of dying stars are being combined to offer new insights into the origin of the intricately-shaped stellar ejecta known as planetary nebulae.