NGC 40

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]

For the Bow Tie Nebula in Centaurus, see Boomerang Nebula.
NGC 40
Emission nebula
Planetary nebula
Observation data: J2000 epoch
Right ascension00h 13m 01.015s[1]
Declination+72° 31′ 19.085″[1]
Distance~3,500 ly (~1.0 kpc)[2] ly
Apparent magnitude (V)10.7,[1] 11.6[2]
Apparent dimensions (V)38 x 35 arcseconds[2]
ConstellationCepheus
DesignationsBow-Tie Nebula, Caldwell 2

References
  1. "NGC 40". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-12-22.
  2. O'Meara, Stephen James (2002). Deep Sky Companions: The Caldwell Objects. Sky Publishing Corporation. pp. 22–23. ISBN 978-0-933346-97-0.
  3. "Chandra X-Ray Observatory". Retrieved 2007-06-05.


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