8 Interesting Wolf Rayet Star Facts

Wolf Rayet Stars are very interesting for astronomers, as they represent some of the rarest stars within our night sky. They represent some of the hottest stars in our universe, and are highly luminous too, so you can often see them in the night sky without a telescope.

But what exactly are Wolf Rayet stars, and how do they differ from other stars in the night sky? Well, let’s look at some of the facts about these types of stars.

1. Wolf Rayet used to be included in the stellar classification group O, which is the hottest. However, they were separate into their own group of stars, classified W, because they lack hydrogen lines. If you aren’t sure about stellar classification, have a look here at more star facts.
2. We then further classify Wolf Rayet stars based on the the strength of the carbon and nitrogen lines, into groups WO, WN, WC and WN/C.
3. However, in spite of this classification, you will probably see Wolf Rayet stars simply referred to as WR stars.
4. They are named Wolf-Rayet stars after French astronomers Charles Wolf and Georges Rayet, who were the first to discovered these stars.
5. The three stars that these astronomers discovered are referred to now as WR 134, WR 135 and WR 137. They are all located in the constellation Cygnus.
6. The temperature of a Wolf Rayet star can be anything from 30,000K all the way up to 210,000K.
7. The most luminous and most massive star in our night sky, R136a1, is a Wolf Rayet star.
8. On average, Wolf Rayet stars are more than 20x the size of our solar systems star, the Sun.
9. At present, we’ve counted around 500 Wolf Rayet stars that are located within our Milky Way Galaxy.

Previously referred to as W-type stars, there are many more than the 500 or so Wolf Rayet stars that we know about in our Milky Way. In saying this, there are only a few thousand potential WP stars in our catalogue, which means that they’re much rarer than other forms of star.

Here you can see EZ Canis Majoris surrounded by the Nebula Sh2-308, also known as the Cosmic Bubble!

WR stars are at a normal stage of their evolution, and they’re usually the result of a red or blue supergiant. Though one of the main things that Wolf Rayet stars are known for is their fairly violent ending.

NASA describes the Wolf Rayet stars like in a simple phrase; they “live fast and die hard”. Wolf Rayet stars actually meet the end of their lives in a massive supernova explosion. The star moves at millions of miles per hour and elements of it are stripped away, which they then explode as a supernova.

The most massive (the star with the largest mass) and the most luminous star in the sky is R136a1, which is located in the Tarantula Nebula of the Large Magellanic cloud. However, the largest star is actually VY Canis Majoris, which isn’t a Wolf Rayet star. Why isn’t it? Well, astronomers do not think it has evolved into the Wolf Rayet classification yet, but it will one day.

As well as R136a1, there are many other well known WR stars in the sky. Probably the best known of these are the stars Theta Muscae and Gamma Velorum. theta Muscae, as you might’ve guessed, is located in the Musca constellation. It’s the second brightest WR star in the sky. Gamma Velorum is a quadruple star system in the constellation Vela, which is the closest WR to our solar system.

Whilst we aren’t entirely sure of how many Wolf Rayet stars there are in our entire galaxy, we know that there are around 500 of them in our Milky Way, which is nothing when you consider how many stars there are in our entire Milky Way.

Wolf Rayet stars are some of the hottest in our universe. Like any extremely hot star with a very high surface temperature, they are colored blue.

Hopefully you’ve learned a little bit more about Wolf Rayet stars with these facts. They make up the brightest and most massive stars in our universe, as well as some of the hottest too! They’re very rare in comparison to other stars, which makes them all the more interesting.