NGC 281, IC 11 or Sh2-184 is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

Perseus Spiral Arm The Perseus Arm is one of two major spiral arms of the Milky Way galaxy. The second major arm is called the Scutum–Centaurus Arm. The Perseus Arm begins from the distal end of the long Milky Way central bar. Previously thought to be 13,000 ligh ...

. This 20×30 arcmin sized nebulosity is also associated with

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

IC 1590, several Bok globules and the multiple star, B 1. It collectively forms Sh2-184, spanning over a larger area of 40 arcmin. A recent distance from radio

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

es of water

maser A maser (, an acronym for microwave amplification by stimulated emission of radiation) is a device that produces coherent electromagnetic waves through amplification by stimulated emission. The first maser was built by Charles H. Townes, Ja ...

s at 22 GHz made during 2014 is estimated it lies 2.82±0.20 kpc. (9200 ly.) from us. Colloquially, NGC 281 is also known as the Pacman Nebula for its resemblance to the video game character.

Edward Emerson Barnard Edward Emerson Barnard (December 16, 1857 – February 6, 1923) was an American astronomer. He was commonly known as E. E. Barnard, and was recognized as a gifted observational astronomer. He is best known for his discovery of the high proper mo ...

discovered the nebula in August 1883, describing it as "a large faint nebula, very diffuse." Multiple star 'B 1' or β 1 was later discovered by

S. W. Burnham Sherburne Wesley Burnham (December 12, 1838 – March 11, 1921) was an American astronomer. For more than 50 years Burnham spent all his free time observing the heavens, mainly concerning himself with binary stars. Biography Sherburne ...

, whose bright component is identified as the highly luminous O6 spectral class star, HD 5005 or HIP 4121. It consists of an 8th-magnitude primary with four companions at distances between 1.4 and 15.7 arcsec. There has been no appreciable change in this quintuple system since the first measures were made in 1875. The nebula region is visible in amateur telescopes from dark sky locations. In his book ''Deep Sky Wonders'',

Walter Scott Houston Walter Scott Houston (May 30, 1912–December 23, 1993) was an American popularizer of amateur astronomy. He wrote the " Deep-Sky Wonders" column in ''Sky and Telescope'' magazine from 1946 to 1993. Biography Houston was born in Tippecanoe, ...

describes the appearance of the nebula in small telescopes: :"There was a faint glow in the immediate vicinity of the multiple star, with an occasional impression of a much larger nebulosity...Its surface brightness was much less than that of M33 in Triangulum or NGC 205, the distant companion of the Andromeda galaxy."

Gallery

References

External links

NGC 281
Astronomy picture of the Day (August 23, 2005) at NASA *
NGC 281 at Deep Space Map
{{DEFAULTSORT:NGC 0281 H II regions Cassiopeia (constellation) 0281 Sharpless objects 18811116 Star-forming regions