I extracted this from Wikipedia, study the finished article for readability. interior the present celebrity type device, the Morgan-Keenan device, the spectrum letter is better with the help of a style from 0 to 9 indicating tenths of the variety between 2 celebrity instructions, so as that A5 is 5 tenths between A0 and F0, yet A2 is two tenths of the finished variety from A0 to F0. yet another length this is blanketed interior the Morgan-Keenan device is the luminosity type expressed with the help of the Roman numbers I, II, III, IV and V, expressing the width of particular absorption lines interior the celebrity's spectrum. this is been shown that this option is a familiar degree of the size of the celebrity, and for this reason of the full luminosity output from the celebrity. type I are oftentimes referred to as supergiants, type III only giants and sophistication V the two dwarfs or greater suitable important series stars. for occasion our solar has the spectral form G2V, that are interpreted as "a 'yellow' 2 tenths in the direction of 'orange' important series celebrity".