The following are a universally-approved standard for classifying stars in our Universe. Please note, however, that some stars are special and therefore do not appear on this register.
Main-sequence stars[]
Class-M[]
Class-M stars are the smallest of the "true" stars, appearing dim and red from a distance. Their planets are usually tidally-locked if they are close in, and gas giants are rare as they disrupt the orbits of other planets as well as the star itself. Moons are rare around planets orbiting M-class stars. They are the coolest and least luminous. Red Dwarfs live for trillions of years, due to low rate of fuel consumption.
Class-K[]
Class-K stars, also known as Orange Dwarfs, are a step up from Red Dwarfs. They appear orange in colour, and often have luminosities ranging from 0.1 to 0.8 L. These stars last longer than most stars, but not as long as Class-M. Due to their luminosities and longivity, habitable planets are most often found around Orange and Yellow Dwarfs.
Class-G[]
Class-G stars, also known as Yellow Dwarfs, are yellow in colour and are the most likely stars in the Universe to host life, due to their stability, longivity and luminosity.
Class-F[]
Class-A[]
Class-B[]
Class-O[]
Giants[]
Yellow giants (G-K)[]
Red giants (M)[]
Carbon stars (C, N, S)[]
AGB Red giants[]
Post-AGB stars (G, F, A, B)[]
High-mass[]
O-type giants[]
B-type giants[]
Supergiants and hypergiants[]
Red supergiants (M)[]
Yellow (or white) hypergiants (A, F, G, K)[]
Yellow supergiants (F, G, K)[]
A-type supergiants[]
B-type supergiants[]
O-type supergiants[]
B-type hypergiants[]
Luminous blue variables[]
Peculiar Stars[]
Wolf-Rayet stars[]
CSPNe[]
Stellar Remants[]
White dwarfs[]
Neutron stars[]
Black holes[]
Anomalous Stars[]
TBA