This image of the Thor's Helmet nebula or NGC 2359 was obtained using the Wide Field Camera on the Isaac Newton Telescope (INT).
It is a three-colour composite made from data collected using filters to isolate the light
emitted by hydrogen alpha (H-alpha), doubly-ionised oxygen (OIII) and single-ionised sulfur (SII) atoms,
and coded in the image as red, green and blue respectively.
Credit: R. Barrena (IAC) and D. López [ JPEG | TIFF
NGC 2359, better known as the Thor's Helmet nebula, is actually more like an interstellar bubble, blown as a fast wind from the bright, massive star near the bubble's center sweeps
through a surrounding molecular cloud. The central star is an extremely hot giant Wolf-Rayet star, thought to be in a brief, pre-supernova stage of evolution.
It lies about 15,000 light years from Earth in the constellation Canis Major, measuring about 30 light years.
It is one of the best known Wolf-Rayet nebular structures, along with NGC 6888, and the name Thor's Helmet is due to its remarkable resemblance to depictions of the headwear
donned by the famed Norse god of thunder. This INT image captures striking details of the nebula's filamentary structures. The bluish colour remarks the strong emission due to oxygen
atoms in the glowing gas. In fact, it can be visually seen with telescopes of moderate aperture using an [OIII] narrow-band filter.