Planetary Nebula Mz3 -- click on the above image to view the full image.

Sometimes stars are surrounded by beautiful gaseous nebulae. These can often be seen even with smaller telescopes and have become a favorite of amateur astronomers. Today, we believe that planetary nebulae are the ejected outer layers of aging middle-weight stars and that our Sun will, in about four and a half billion years, eject its own planetary nebula.

Planetary nebulae come in many shapes but most of them are not spherical. Many theories try and explain why a spherical star might blow a non-spherical nebula. One of these theories says that a companion orbiting the aging star helped shape the nebula. Companions to the central stars of planetary nebulae, however, are relatively rare.

Recently, however, a new search for close companions revealed that most central stars might have them. If so, this not only explains the non-spherical shape of the nebulae, but might also reveal a that single stars do not create planetary nebulae at all. This implies that our Sun might not blow planetary nebulae after all. This might also mean that binarity plays a larger role in stellar evolution than previously imagined.

This work was carried out by Orsola De Marco, with collaborators Howard Bond.