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.^[2]

Bipolar planetary nebula PN Hb 12.^[1]

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.^[3]

Examples

Planetary Nebula M2-9, otherwise known as the Twin Jet Nebula or the Wings of a Butterfly Nebula, is a bipolar nebula.

• Homunculus Nebula around Eta Carinae^[4][5][6][7]
• Hubble 5^[8]
• M2-9 – The Wings of a Butterfly Nebula^[9][10][11]
• OH231.8+4.2 – The Calabash Nebula or Rotten Egg Nebula^{[12][13][14][15]}
• Mz3 (or Menzel 3) – The Ant Nebula^[16][17][18]
• CRL 618 – The Westbrook Nebula^[19]
• CRL 2688 – The Egg Nebula^{[20][21][22][23]}
• HD 44179 – The Red Rectangle Nebula^[24][25][26]
• MyCn18 – The Engraved Hourglass Nebula^{[27][28][29][30][31]}
• He2-104 – The Southern Crab Nebula^[32][33][34]
• The Boomerang Nebula^{[35][36][37][38][39]}
• NGC 2346 – Also known as the Butterfly Nebula^[40]
• NGC 6302 – The Bug or Butterfly Nebula
• KjPn 8 Nebula – The largest (in angular size) bipolar planetary nebula.^[41]