Thor’s Helmet: A Hot Star by Any Other Name

Thor's Helmet, courtesy

Astronomers love to give evocative names to the objects they observe. That’s why we hear about things like the Ring Nebula and the Cat’s-Eye Nebula. Sure, the things they describe look like the name, although the monickers don’t always have much to do with the intrinsic nature of the object.

I recently ran across a really exciting-looking image of a bubble of gas being blown out by a Wolf-Rayet star. WRs are extremely hot (25,000-50,000 K), energetic stars that blast their outer layers away at thousands and thousands of miles per second. incredibly hot (25,000-50,000K) and expel their outer layers of gas at tremendous velocities (thousands of kilometers per second). It’s about 15,000 light-years away in the direction of the constellation Canis Major (the Big Dog). But, because it’s so bright and energetic, we can see it very nicely.


  1. Renee

    Ms Petersen,
    I enjoyed your web site.
    Wolf-Rayet stars are favorites of mine. I believe the picture used in your article, “Thor’s Helmet: A Hot Star by Any Other Name” is the Bubble Nebula NGC 7635. Thor’s Helmet is NGC 2359. NASA publishes pictures daily; the URL for a picture similar to the one in your article is

    There are pictures of Thor’s Helmet at and

    Hope this helps.

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