Stars are hot, massive, and luminous celestial objects in plasma state. Observed masses of stars range from 0.01 MΘ to 100 MΘ where MΘ is the solar mass and we have MΘ = 1.989x1033 gram. Stars with masses greater than 100MΘ may also exist. But their lifetime is very short, being of the order of 106 years. Harm & Schwarzschild  has shown that the maximum possible mass of a stable normal stars is 60 MΘ . There is a bit uncertainty in the minimum mass of a star. It is believed that stars with mass less than 0.01 MΘ can also exist. But they will never be main sequence stars. Because their interior will not be hot enough to burn hydrogen . They will shrink directly to the while dwarf state.