There are seven different types of stars that vary in color and composition.
The classifications usually fall under the names of A, O, B, K, F, G, and M. The type A star is a main sequence that is also known as a dwarf star and it usually has a blue color with a composition of hydrogen (H) lines strongest for A0 stars, decreasing for other A’s. It has a mass of 3.
2 with a radius of 2.5 and an average luminosity of 80. Two examples of star type A are Sirius and Vega. Another type of star would be star type O which is a main sequence star that also has a blue color and has a composition of singly ionized helium lines (H I) either in emission or absorption including a strong UV continuum. It has a mass of 60 with a radius of 15 and an average luminosity of 1,400,000. An example of this star is 10 Lacertae.
Star type B is another type of star that falls into the main sequence star description and has a blue color with a composition of neutral helium lines (H II) in absorption. The mass of this star type is 18 with a radius of 7 and an average luminosity of 20,000 and one example of this star is Rigel Spica. The other half of the star types luckily fall under different categories. For example, star type K is a main sequence star but, it’s also known as an orange dwarf star with an orange to red color and a composition of metallic lines with some blue continuum. The mass is 0.8 with a radius of 0.9 and an average luminosity of 0.
4. An example would be Arcturus and Aldebaran. Star type F has a blue to white color, a mass of 1.7, a radius of 1.3, an average luminary of 6, a composition of Ca II absorption where metallic lines become noticeable, and it is known as a yellow-white dwarf main sequence star. Two examples would be Canopus and Procyon. Star type G has a white to yellow color, a mass of 1.1, a radius of 1.
1, an average luminary mass of 1.2, a composition of absorption lines with neutral metallic atoms and ions (e.g. once-ionized calcium), and it is known as a yellow dwarf star. Two examples would be the Sun and Capella. Finally star type M has a composition of some molecular bands of titanium oxide with a red color, a mass of 0.
3 , a radius of 0.4, and an average luminary of 0.04 which makes it seem very faint.
It is classified as a red dwarf star with Betelgeuse and Antares being two examples of it.Every star goes through a certain life cycle which is why you might see stars changing as they get older. First a star is formed through matter in a nebula where different pieces start to clump together to form matter. This is called a protostar when the clumps contract to a spherical shape. As it starts to heat up the particles move faster eventually forming a star. During a stars life it produces light and energy and they also expand and contract as a cycle in their lifetime.
When fusion stops occurring a stars life comes to an end because they begin to contract and this causes the result of either a white dwarf, a supernova, a neutron star, or a black hole. So as you can see, as a star gets older it undergoes age causing it to basically erode eventually into nothing but sometimes stars just turn into red giant stars or white dwarfs.
