Helium star

A helium star is a very hot, blue star. These stars have strong signs of the element helium and weaker signs of hydrogen. This shows scientists that these stars lose a lot of their outer layers into space because of strong winds from their surfaces.

There is a special group of helium stars called extreme helium stars. These stars do not show any hydrogen at all. Instead, they are made almost entirely of helium.

Pure helium stars follow a path in space that is similar to the path of more common stars that are mostly made of hydrogen. Scientists call this path the helium main sequence. It is like a roadmap that helps us understand how these stars live and change over time.

Terminology

Earlier, the term "helium star" was used for a B-type star, but this is not its common meaning anymore.

Today, a helium star can also mean a special kind of star. This can happen if two helium white dwarfs come together. If these two white dwarfs have enough mass—about half the weight of our Sun—they might start a new kind of energy production using helium. This kind of star would only last for a few hundred million years. Scientists think this might be how extreme helium stars are created.

Description

A helium star is a special kind of star that shines very brightly and is very hot. These stars are different from most stars because they have a lot of helium and not much hydrogen. They can be found on a special line in a diagram that helps scientists understand stars, called the helium main sequence. This line is close to where other stars are found but is usually a bit hotter.

Scientists have watched these stars change over time. One example is a star that exploded in a faraway galaxy. This happened when a small, dense star called a white dwarf got extra material from a helium star nearby. These stars might also change into bigger, cooler stars in the future after losing their outer layers.