| NGC 7662 | |
|---|---|
A Hubble Space Telescope (HST) image of NGC 7662. Credit: HST/NASA/ESA.[1] |
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| Observation data (Epoch J2000) |
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| Right ascension | 23h 25m 54s[2] |
| Declination | +42° 32′ 6″[2] |
| Distance | ~2000-6000 ly |
| Apparent magnitude (V) | 8.6[3] |
| Apparent dimensions (V) | 37″ |
| Constellation | Andromeda |
| Physical characteristics | |
| Radius | 0.8 ly |
| Other designations | PK 106-17 1, GCRV 14695, PN ARO 20, Blue Snowball Nebula, Snowball Nebula, Caldwell 22 |
| See also: Planetary nebula, Lists of nebulae | |
Coordinates: 23h 25m 54s, +42° 32′ 6″
NGC 7662 (also known as the Blue Snowball Nebula, Snowball Nebula or Caldwell 22) 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.[4] 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.[5]
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.
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