NGC 2359 is an emission nebula

Emission nebula

An emission nebula is a cloud of ionized gas emitting light of various colors. The most common source of ionization is high-energy photons emitted from a nearby hot star...

  in the constellation Canis Major

Canis Major

Canis Major is one of the 88 modern constellations, and was included in the 2nd-century astronomer Ptolemy's 48 constellations. Its name is Latin for 'greater dog', and is commonly represented as one of the dogs following Orion the hunter...

. The nebula is approximately 15,000 light-years away and 30 light years in size. Known as a Wolf-Rayet star

Wolf-Rayet star

Wolf–Rayet stars are evolved, massive stars , which are losing mass rapidly by means of a very strong stellar wind, with speeds up to 2000 km/s...

, the central star is an extremely hot giant thought to be in a brief, pre-supernova

Supernova

A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...

 stage of evolution. It is similar in nature to the Bubble Nebula, interactions with a nearby large molecular cloud are thought to have contributed to the more complex shape and curved bow-shock structure of Thor's Helmet.

It is also Sharpless catalog

Sharpless catalog

The Sharpless catalog is a list of 312 HII regions , intended to be comprehensive north of declination -27°. The first edition was publishing 1953 with 142 objects and second and final version was published by US astronomer Stewart Sharpless in 1959 with 312 objects.In 1953 Stewart Sharpless joined...

 Sh2-298 and Gum catalog

Gum catalog

The Gum catalog is an astronomical catalog of 84 emission nebulae in the southern sky. It was made by the Australian astronomer Colin Stanley Gum at Mount Stromlo Observatory using wide field photography. Gum published his findings in 1955 in a study entitled A study of diffuse southern H-alpha...

 4.

External links

• Astronomy Picture of the Day
  Astronomy Picture of the Day
  Astronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
  
  - Search for NGC 2359
• Thor's Helmet from CFHT
• astrosurf.com
• Kopernik image
• Encyclopedia article