NGC 40

NGC 40

NGC 40
Observation data
(Epoch J2000)
Right ascension 00h 13m 01.015s[1]
Declination +72° 31′ 19.085″[1]
Distance ~3,500 ly (~1.0 kpc)[2]
Apparent magnitude (V) 11.4,[1] 12.3[2]
Apparent dimensions (V) 38 x 35 arcseconds[2]
Constellation Cepheus
Physical characteristics
Other designations Bow-Tie Nebula, Caldwell 2

NGC 40 (also known as the Bow-Tie Nebula and Caldwell 2) is a planetary nebula discovered by William Herschel on November 25 1788, and is composed of hot gas around a dying star. The star has ejected its outer layer which has left behind a smaller, hot star with a temperature on the surface of about 50,000 degrees Celsius.[3] Radiation from the star causes the shed outer layer to heat to about 10,000 degrees Celsius,[3] and is about one light-year across.[3] About 30,000 years from now, scientists theorize that NGC 40 will fade away, leaving only a white dwarf star approximately the size of Earth.[3]



  1. ^ a b c "SIMBAD Astronomical Database". Results for NGC 40. Retrieved 2006-12-22. 
  2. ^ a b c O'Meara, Stephen James (2002). Deep Sky Companions: The Caldwell Objects. Sky Publishing Corporation. pp. 22–23.  
  3. ^ a b c d "Chandra X-Ray Observatory". Retrieved 2007-06-05. 

External links

  • NGC 40 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images