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.The Macquarie/AAO/Strasbourg Hα Planetary Nebula Catalogue: MASH, Parker et al. 2006, MNRAS, 373, 79
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.Binary Progenitor Models for Bipolar Planetary Nebulae, Soker 1998, ApJ, 496, 833
Examples
Homunculus Nebula around Eta CarinaeNewsCenter – Doomed Star Eta Carinae (06/10/1996) – Release Images. HubbleSite (10 June 1996). Retrieved on 26 November 2010.Eta Carinae Nebula (NGC 3372). Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. Hubble 5HubbleSite – NewsCenter – Hubble Witnesses the Final Blaze of Glory of Sun-Like Stars (12/17/1997) – Release Images Hubble 12 M2-9 – The Wings of a Butterfly NebulaButterfly Nebula (M 2-9). Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. OH231.8+4.2 – The Calabash Nebula or Rotten Egg NebulaNewsCenter – The "Rotten Egg" Nebula: A Planetary Nebula in the Making (10/19/1999) – Introduction. HubbleSite (19 October 1999). Retrieved on 26 November 2010.APOD: 1 November 1999 – The Rotten Egg Planetary Nebula. Antwrp.gsfc.nasa.gov (1 November 1999). Retrieved on 26 November 2010.Calabash Nebula (OH231.8+4.2). Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. Mz3 (or Menzel 3) – The Ant NebulaNewsCenter – Astro-Entomology? Ant-like Space Structure Previews Death of Our Sun (02/01/2001) – Introduction. HubbleSite (1 February 2001). Retrieved on 26 November 2010.Ant Nebula (Menzel 3). Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. CRL 618 – The Westbrook Nebula CRL 2688 – The Egg NebulaNewsCenter – Hubble Finds Searchlight Beams and Multiple Arcs around a Dying Star (01/16/1996) – Introduction. HubbleSite (16 January 1996). Retrieved on 26 November 2010.Egg Nebula (CRL 2688). Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. HD 44179 – The Red Rectangle NebulaNewsCenter – Dying Star Sculpts Rungs of Gas and Dust (05/11/2004) – Release Images. HubbleSite (11 May 2004). Retrieved on 26 November 2010.Red Rectangle. Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. MyCn18 – The Engraved Hourglass NebulaNewsCenter – Hubble Finds an Hourglass Nebula around a Dying Star (01/16/1996) – Release Images. HubbleSite (16 January 1996). Retrieved on 26 November 2010.Hourglass Nebula (MyCn 18). Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. – The Southern Crab NebulaNewsCenter – Symbiotic Star Blows Bubbles into Space (08/24/1999) – Release Images. HubbleSite (24 August 1999). Retrieved on 26 November 2010.Southern Crab Nebula (He2-104) . Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. The Boomerang NebulaNewsCenter – Hubble Catches Scattered Light from the Boomerang Nebula (09/13/2005) – Release Images. HubbleSite (13 September 2005). Retrieved on 26 November 2010.Boomerang Nebula. Daviddarling.info (1 February 2007). Retrieved on 26 November 2010. NGC 2346 – Also known as the Butterfly NebulaAPOD: 28 October 2001 – NGC 2346: A Butterfly-Shaped Planetary Nebula NGC 6302 – The Bug or Butterfly Nebula KjPn 8 Nebula – The largest (in angular size) bipolar planetary nebula.
References
See also Bipolar outflow Stellar evolution