Wolf–Rayet star facts for kids

Wolf–Rayet stars (often called WR stars) are very old and super big stars. They start out being more than 20 times heavier than our own Sun! These stars are special because they lose a lot of their material very quickly.

Imagine a strong wind blowing from the star. This "stellar wind" can be super fast, up to 2,000 kilometers per second! To give you an idea, our Sun loses a tiny bit of its mass each year, like a speck of dust. But Wolf–Rayet stars lose a huge amount, about 100 million times more mass than the Sun every year.

Wolf–Rayet stars are also incredibly hot. Their surfaces can be between 30,000 K and 200,000 K (that's Kelvin, a way to measure temperature). Because they are so hot, they look blue. They also shine with a lot of energy, much more than the Sun – sometimes millions of times brighter! However, you might not see them as super bright with your eyes because most of their light is in invisible forms, like ultraviolet light and even X-rays.

What is Star Brightness?

When we talk about how bright a star is, there are a few ways to think about it.

How Much Energy a Star Gives Off

In astronomy, luminosity is a fancy word for the total amount of energy a star or other space object gives off. Think of it like a light bulb's power, measured in watts. Our Sun, for example, gives off a huge amount of energy, which we call 1 solar luminosity. This is the basic way scientists measure how powerful a star is.

How Bright a Star Looks

Apparent magnitude is how bright a star looks to us from Earth. This depends on how much light it gives off and how far away it is. A very bright star far away might look dimmer than a less bright star that is closer.

Absolute magnitude is different. It tells us how bright a star truly is, no matter how far away it is from us. It's like comparing all stars from the same distance.

Images for kids

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  Spectrum of WR 137, one of the first Wolf–Rayet stars studied.

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  GK Persei (Nova Persei 1901), a star that showed Wolf–Rayet features in its light.

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  WR 22 in the beautiful Carina Nebula.

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  An artist's drawing of a huge gas disk around the massive star WR 122.

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  AB7 creates one of the brightest glowing clouds in the Magellanic Clouds.

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  WR 31a is surrounded by a blue bubble of gas. This bubble was made by the star's strong wind hitting material it threw off earlier in its life.

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  HD 184738, also known as Campbell's Star. This is actually a planetary nebula, and its central star is an old, small star, unlike the big Wolf–Rayet stars.

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  Hubble Space Telescope picture of nebula M1-67 around the Wolf–Rayet star WR 124.

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  WR 136 is a WN6 star. The gas it shed when it was a red supergiant was hit by the hot, fast winds from the Wolf–Rayet star, forming the visible Crescent Nebula.

See also

In Spanish: Estrella de Wolf-Rayet para niños