H-R Diagram Discipline: EducationHaving the information about spectral types was useful, but astronomers wanted to look for trends in the data. In 1911 Ejnar Hertzsprung plotted the absolute magnitude of stars against their colors. Two years later Henry Norris Russell independently did a similar graph using spectral types. Graphs of this type are known as Hertzsprung-Russell diagrams or H-R diagrams.Tags: starsluminositytemperatureHertzsprungRussellwhite dwarfblue giantsred giantssupergiants
Brightness defined in more detail Brightness is described and measured in terms of radiant flux received from a celestial object. Radiant flux is the total amount of light energy (joules) that crosses one square meter per second. Radiant flux, F, is measured in watts. Radiant flux received from an object depends both on its distance, and on its luminosity. Luminosity is a measure of how much energy an object emits per second.
