THOR’S HELMET

NGC 2359, also known as Thor’s Helmet is an emission/reflection nebula in the constellation of Canis Major. It is quite faint at magnitude +11.5 and is about 12,000 light years distant. It is a fairly small object; only about 6 x 8 arc minutes. It is an interstellar bubble, blown as a fast wind from its bright central star, WR7. The central star is a Wolf-Rayet star - a massive giant probably in a pre-supernova stage in its life. These types of stars are extremely hot (as much as 50,000 - 100,000 K) and expel their outer layers at velocities up to thousands of km/sec. The neubla itself is about 30 light years in size.