• Question: How many types of stars are there in the world?

    Asked by PEACHESSSSSSSSSSSSSSSSSSS to Emma, Alice on 16 Mar 2016.
    • Photo: Alice Harpole

      Alice Harpole answered on 16 Mar 2016:

      All stars are unique, with different masses and made up of different elements. However, much like how we group similar plants and animals into different classes and species, we also group stars with similar characteristics into different classes.

      Before a star is born, it forms a very hot ball of gas called a ‘protostar’. It will then start burning fuel in its core and become a star like our Sun. We call these ‘main sequence stars’. As it starts running out of fuel, the outer layers expand and it will become a giant star (or, if it is really massive, a supergiant).

      When stars finally run out of fuel, they collapse and turn into an array of different objects (depending on their mass). Stars like our Sun become white dwarfs, slightly more massive stars become neutron stars, and really really massive stars become black holes.

      Again, much like plants and animals, we can further divide these types up into more specific groups: we classify main sequence stars by how hot and how bright they are (giving us their ‘colour’ and luminosity classes). Giant stars can be divided into their colour, giving us red giants, yellow giants, blue supergiants…. There are also lots of different labels we can give stars who display different behaviours (usually because they are interacting with their environments), such as Cepheid variables, T Tauri stars etc.