Bipolar nebula



A bipolar nebula is a type of nebula characterized by two lobes either side of a central star. About 10-20% of planetary nebulae are bipolar.

Formation
Though the exact causes of this nebular structure are not known, it is often thought to imply the presence of a binary central star with a period of a few days to a few years. As one of the two stars expelled its outer layers, the other disrupted the outflow of material to form the bipolar shape.

Examples



 * Homunculus Nebula around Eta Carinae
 * Hubble 5
 * M2-9 – The Wings of a Butterfly Nebula
 * OH231.8+4.2 – The Calabash Nebula or Rotten Egg Nebula
 * Mz3 (or Menzel 3) – The Ant Nebula
 * CRL 618 - The Westbrook Nebula
 * CRL 2688 – The Egg Nebula
 * HD 44179 – The Red Rectangle Nebula
 * MyCn18 – The Engraved Hourglass Nebula
 * – The Southern Crab Nebula
 * The Boomerang Nebula
 * NGC 2346 – Also known as the Butterfly Nebula
 * NGC 6302 – The Bug or Butterfly Nebula
 * KjPn 8 Nebula – The largest (in angular size) bipolar planetary nebula.