NGC 281

NGC 281

Emission nebula
H II region
File:NGC 281 from Chandra.jpg NGC 281 in the optical (red, yellow) and X rays (blue)
Observation data: J2000.0 epoch
Right ascension	00h 52m 59.3s
Declination	+56° 37′ 19″
Distance	9500 ly   (2900 pc)
Apparent dimensions (V)	35′
Constellation	Cassiopeia
Physical characteristics
Radius	48 ly
Notable features	open cluster IC 1590, the multiple star HD 5005, and several Bok globules
Designations	IC 11, Sharpless 184, Pacman Nebula

NGC 281 is an H II region in the constellation of Cassiopeia and part of the Perseus Spiral Arm. It includes the open cluster IC 1590, the multiple star HD 5005, and several Bok globules. Colloquially, NGC 281 is also known as the Pacman Nebula for its resemblance to the video game character.

The nebula was discovered in August 1883 by E. E. Barnard, who described it as "a large faint nebula, very diffuse." The multiple star HD 5005, also called $\beta1$, was discovered by S. W. Burnham. It consists of an 8th-magnitude primary with four companions at distances between 1.4 and 15.7 seconds of arc. There has been no appreciable change in this quintuple system since the first measurements were made in 1875.

The nebula is visible in amateur telescopes from dark sky locations. In his book Deep Sky Wonders, Walter Scott Houston 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

• IC 1590 HST.jpg

  Young open star cluster IC 1590, which is found within the star formation region NGC 281

• NGC281NBHunterWilson.jpg

  NGC 281 - Amateur Narrowband Image ([SII] = Red, H-alpha = Green, [OIII] = Blue)

• The Pacman Nebula.jpg

  Composite image of NGC 281

External links

• NGC 281 Astronomy picture of the Day (August 23, 2005) at NASA
• NGC 281 at ESA/Hubble