NGC281 known as the Pacman Nebula taken from Al Sadeem Observatory October 12, 2018 using Vixen ED115S telescope and ZWO1600MC-cool CMOS camera mounted on Skywatcher EQ6. 2.5 hours total exposure time, stacked and post-processed in Pixinsight. (Image Credit: Al Sadeem Astronomy)
NGC281, also known as the Pacman Nebula is an emission nebula located about 9200-9500 light-years away from Earth in the constellation of Cassiopeia (the queen). It is also called IC 11 or Sh2-184 using the IC and Sharpless sky catalogues respectively. Specifically, it is a bright HII region,spans about 96 light-years in diameter (a region in space where interstellar atomic hydrogen is ionized signifying active star formation) within the Milky Way’s Perseus Spiral Arm.
It consists of the open star cluster IC1590, the multiple star B1 and several Bok globules (small, dark dense regions of interstellar dust and gas). It was discovered by the American astronomer E.E. Barnard in August 1883, who described it as “a large faint nebula, very diffuse”.
A portion of the nebula is being obscured by dense interstellar dust and gas, creating a gap like a “mouth” as observed in visible spectrum, resembling the shape of the video game character Pacman, to which the nebula’s name was derived. On the other hand, the unobscured side contains thousands of young high-mass stars, about more than 8 solar masses which produce vast amounts of energy and radiation, illuminating its surrounding cloud.
With the apparent magnitude of +7.4, it cannot be easily seen with the naked eye. You need at least a 4 inch telescope or higher to spot it. Like any other nebula, it will only appear as a faint smudge with several bluish-white stars scattered in view when observed visually. Long-exposure photography is necessary to reveal more stars and its reddish nebulosity, or more preferably using narrowband H-alpha and/or OII) filters (either, where most details are resolved. The nebula is located 00h 52m 59.3s right ascension and 56° 37′ 19” declination. The nebula can be spotted using the bright stars Shedar or Achird as guide stars as they placed few degrees away (see figure below).
REFERENCES
Biggs, B. (2013, October 14). The Pacman Nebula | Space Facts – Astronomy, the Solar System & Outer Space | All About Space Magazine. Retrieved from https://www.spaceanswers.com/deep-space/the-pacman-nebula/
Jones, T. (2018, September 18). NGC 281 – The Pacman Nebula. Retrieved from https://astrobackyard.com/ngc-281-the-pacman-nebula/
Wager, S. (n.d.). NGC281 Pacman nebula. Retrieved from https://www.swagastro.com/ngc281.html
Wikipedia contributors. (2018, March 4). NGC 281. In Wikipedia, The Free Encyclopedia. Retrieved from https://en.wikipedia.org/w/index.php?title=NGC_281&oldid=828672184