Use Magnitudes to Describe Brightness and Color
M m 5 log 10 pcR where Ris the distance of the star in parsecs. A magnitude 4 star is 25 times brighter than a magnitude 5 star. Voyages Magnitude The surface temperature of a star determines the color of light it emits. . This works well for stars similar to the Sun which is why it is the standard measure for color in Hertzsprung-Russell diagrams. Brightness and magnitude are important. Since color and temperature and spectral type are all equivalent we can plot the color of a star against its brightness measured in magnitudes as a way of building an H-R diagram without taking the stars spectrum. μ B 2705 25 log. The magnitude scale is a much more convenient way to express brightness measurements than using actual brightness measurements that use much larger numbers. I B My guess is that the 2705 comes from conversion factors but I. In practice the magnitude of a celestial object is measured in certain wa...