If you include all three of the smallest (R,N,S) it ismatt.o said:oh be a fine girl kiss me now slap
A common mnemonic for remembering the classes of stars is "Oh Be A Fine Girl/Guy, Kiss Me Right Now Sweetheart", with each letter representing a class: O (O-type), B (B-type), A (A-type), F (F-type), G (G-type), K (K-type), M (M-type), R (red dwarf), N (neutron star), S (supergiant).
There are seven classes of stars - O, B, A, F, G, K, and M - with additional subclasses for some of these.
The O, B, and A classes are known as "hot" stars, while the F, G, K, and M classes are known as "cool" stars. The classification is based on a star's temperature, color, and spectral lines. O-type stars are the hottest and have a blue-white color, while M-type stars are the coolest and have a red color.
Stars are classified based on their spectral characteristics, which include temperature, color, and spectral lines. This allows scientists to categorize stars into distinct classes based on their similarities and differences.
Knowing the class of a star allows scientists to understand its physical properties, such as its temperature, size, and luminosity. This information can also provide insights into a star's evolution and lifespan. Additionally, star classification helps astronomers in their search for habitable planets and in understanding the overall structure and composition of the universe.