World Library  
Flag as Inappropriate
Email this Article

Egg Nebula

Article Id: WHEBN0000933783
Reproduction Date:

Title: Egg Nebula  
Author: World Heritage Encyclopedia
Language: English
Subject: Wide Field and Planetary Camera 2, Astronomy/Picture/July 2005, List of protoplanetary nebulae, Bipolar nebula, Cygnus (constellation)
Publisher: World Heritage Encyclopedia

Egg Nebula

Egg Nebula
Reflection nebula
Protoplanetary nebula
RAFGL 2688, the Egg Nebula
Observation data: J2000 epoch
Right ascension 21h 02m 18.75s[1]
Declination +36° 41′ 37.8″[1]
Distance approx[2] 3000 ly   (920 pc)
Apparent magnitude (V) 14.0[1]
Apparent dimensions (V) 30″ × 15″
Constellation Cygnus
Physical characteristics
Radius 0.2[a] ly
Absolute magnitude (V) 4.2[b]

RAFGL 2688,[1] The Egg,[1]

Cygnus Egg[1]

The Egg Nebula (also known as RAFGL 2688 and CRL 2688) is a bipolar protoplanetary nebula approximately 3,000 light-years away from Earth. Its peculiar properties were first described in 1975 using data from the 11 µm survey obtained with sounding rocket by Air Force Geophysical Laboratory (AFGL) in 1971 to 1974. (Previously, the object was catalogued by Fritz Zwicky as a pair of galaxies.)

The Egg Nebula's defining feature is the series of bright arcs and circles surrounding the central star. A dense layer of gas and dusts enshrouds the central star, blocking its direct light from our view. However, the light from the central star penetrates the thinner regions of this dusty enclosure, illuminating the outer layers of gas to create the arcs seen in this resplendent image (Hubble Site).

The dusty enclosure around the central star is very likely a disc. The bipolar outflows in the image indicate that the system has angular momentum, which is very likely generated by an accretion disc. In addition, a disc geometry would account for the varying thickness of the enclosure that allows light to escape along the disc's axis and illuminate the outer layers of gas, but still blocks it from our direct view along the disc edge. Although dusty discs have been confirmed around several post-AGB objects (S. De Ruyter et al., 2006), a disc around the Egg Nebula is yet to be confirmed.

The Egg Nebula was photographed by the Wide Field and Planetary Camera 2 of the NASA/ESA Hubble Space Telescope.

The Egg Nebula emits polarized light[3] which can also be detected visually by a medium-sized telescope.[4]


  • Gallery 1
  • Notes 2
  • References 3
  • External links 4



  1. ^ distance × sin ( diameter_angle / 2 ) = 0.2 ly. radius
  2. ^ 14.0[1] apparent magnitude - 5 * (log10(920 pc distance) - 1) = 4.2 absolute magnitude


  1. ^ a b c d e f g "SIMBAD Astronomical Database". Results for Egg Nebula. Retrieved 2007-01-05. 
  2. ^ a b "Hubble Images Searchlight Beams from a Preplanetary Nebula". ESA/Hubble Picture of the Week. Retrieved 24 April 2012. 
  3. ^ Raghvendra Sahai; et al. (January 1998). "The Structure of the Prototype Bipolar Protoplanetary Nebula CRL 2688 (Egg Nebula): Broadband, Polarimetric, and H2 Line Imaging with NICMOS on the Hubble Space Telescope". The Astrophysical Journal Letters 492 (2): L163–L167.  
  4. ^ "Proto-planetary Nebulae". Retrieved 6 July 2013. 
  • Hubble Finds Searchlight Beams and Multiple Arcs around a Dying Star. STScI Press release: Space Telescope Science Institute. January 16, 1996.
  • De Ruyter et al. Keplerian discs around post-AGB objects: a common phenomenon? Astronomy & Astrophysics 448, 641–653 (2006).

External links

  • Merrifield, Michael. "Egg Nebula". Deep Space Videos.  
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.