Helium star

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

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

Pure helium stars follow a path in space that is similar to the path taken by 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 to describe a B-type star, but this is no longer the common meaning.

Today, a helium star can also refer to a special kind of star that might form if two helium white dwarfs come together. If these two white dwarfs have enough mass—about half the weight of our Sun combined—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 process could 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 explosion 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.