Blue Snowball Nebula

NGC 7662

Nebula
A Hubble Space Telescope (HST) image of NGC 7662. Credit: HST/NASA/ESA.
Observation data: J2000 epoch
Right ascension	23h 25m 54s
Declination	+42° 32′ 6″
Distance	~2000-6000 ly ly
Apparent magnitude (V)	8.6
Apparent dimensions (V)	37″
Constellation	Andromeda
Physical characteristics
Radius	0.8 ly ly
Designations	PK 106-17 1, GCRV 14695, PN ARO 20, Blue Snowball Nebula, Snowball Nebula, Caldwell 22
See also: Lists of nebulae

Coordinates: 23^h 25^m 54^s, +42° 32′ 6″

NGC 7662, also known as the Blue Snowball Nebula or Snowball Nebula, is a planetary nebula located in the constellation Andromeda.

The distance to this nebula is not known with any real accuracy. According to the Skalnate Pleso Catalogue (1951) the distance of NGC 7662 is about 1,800 light years, the actual diameter about 20,000 AU. In a more recent survey of the brighter planetaries, C.R.O'Dell (1963) derived a distance of 1,740 parsecs or about 5,600 light years, increasing the actual size to 0.8 light year, or nearly 50,000 AU. It has a faint central star that is variable, with a magnitude range of 12 to 16. The central star is a bluish dwarf with a continuous spectrum and a computed temperature of about 75,000K. The nuclei of the planetary nebulae are among the hottest stars known.

NGC 7662 is a popular planetary nebula for casual observers. A small telescope will reveal a star-like object with slight nebulosity. A 6" telescope with a magnification around 100x will reveal a slightly bluish disk, while telescopes with a primary mirror at least 16" in diameter may reveal slight color and brightness variations in the interior.