At a Glance: Shapes of Planetary Nebulae

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All planetary nebulae form during the death of a Sun-like star. So why do they have different shapes? 

Planetary Nebulas
Produced by the Space Telescope Science Institute’s Office of Public Outreach.
All images, illustrations, and videos courtesy of NASA, ESA, and STScI except:
·       Sun rotation movie courtesy of NASA/STEREO
·       Animation of Sun becoming a red dwarf courtesy of ESA/Hubble (M. Kornmesser & L. L. Christensen)
·       Animation of a planetary nebula’s expansion courtesy of ESA/Hubble (M. Kornmesser)
·       Planetary nebula fly-around animation courtesy of ESA/Hubble (M. Kornmesser)
·       Taurus constellation drawing from Firmamentum Sobiescianum sive Uranographia by Johannes Hevelius, courtesy of the United States Naval Observatory
·       Abell 39 image courtesy of WIYN/NOAO/NSF
·       Bipolar planetary nebula formation animation by Thomas Goertel (STScI)
·       Garden Sprinkler Nebula image courtesy of ESA, A. Riera (Universitat Politecnica de Catalunya, Spain) and P. Garcia-Lario (European Space Agency ISO Data Centre, Spain)
·       Garden sprinkler animation courtesy of ESA/Hubble (M. Kornmesser & L. L. Christensen)
·       Saturn Nebula (NGC 7009) image courtesy of Brad Ehrhorn/Adam Block/NOAO/AURA/NSF
·       Photo of observatory dome courtesy of Phil Massey, Lowell Observatory/NOAO/AURA/NSF
·       Animation of Hubble Space Telescope over Earth courtesy of ESA/Hubble (M. Kornmesser & L. L. Christensen)
·       Cat’s Eye Nebula ground-based image courtesy of Bruce Balick, University of Washington
·       Ring Nebula ground-based image courtesy of Daniel Folha and Simon Tulloch, Isaac Newton Group of Telescopes, La Palma
·       Helix Nebula ground-based image copyright Edward M. Henry
·       Image of Magellanic Clouds courtesy of ESO/C. Malin
·       Image of Large Magellanic Cloud © Australian Astronomical Observatory; photograph by David Malin
Written by Vanessa Thomas and John Stoke
Designed by John Godfrey 
Music courtesy of Association Production Music


 at-a-GLANCE. Shapes of planetary nebulae. 

4 different-shaped nebulae bloom 

Planetary nebulae have many different shapes. 

But all planetary nebulae form during the death of a Sun-like star. 

So why do they have different shapes? 

Shapes of planetary nebulae: Round, elliptical, bipolar, and complex 

Round planetary nebulae probably form when stars eject their outer layers, more or less evenly in all directions. 

Stellar winds, streams of particles from the star, might blow stronger in one direction, making some planetary nebulae elongated or "elliptical." 

Bipolar planetary nebulae might be created by a star that has an unseen companion. 

The two stars orbit each other. Near the end of its life, the Sun-like star swells, "swallowing" the smaller star! 

This makes the big star spin faster and it throws off a ring of gas and dust. 

The ring forces stellar winds into jets above and below the ring. 

Planetary nebulae with complex shapes might be made by stars with wobbling jets. 

These wandering jets funnel material away from the star in various directions rather like a loose, rotating garden sprinkler. 

The jets might be made to wobble by the gravitational tug of a second star.