The Hertzsprung-Russell Diagram

HR Diagrams The Hertzsprung-Russell Diagram, otherwise known as HR diagram, is a graph that shows many patterns and properties of stars based on plotting them by their temperature on the surface and their light they emit, or luminosity. Created in 1912, the HR diagram was made by two astronomers, Ejnar Hertzsprung and Henry Russell who found patterns with stars’ properties. The Hertzsprung-Russell Diagram shows how every star goes through different evolutionary stages. These evolutionary stages are based on the internal structure of the star and how the star produces energy. On the graph, the different evolutionary stages can clearly be seen. When looking at an HR diagram, the stars can have their evolutionary stage identified based on the region in which they are plotted. The stars that are located on a diagonal line from the upper left to the bottom right are called main sequence stars. Stars are part of the main sequence for 90% of their lives while they …show more content…
The seven spectral classes are identified with the letters O, B, A, F, G, K and M. O describes stars with a temperature of 50,000 Kelvin that are red. At half the temperature, stars that are yellow are classified with B. Next up, is A which includes stars with a surface temperature of 10,000 Kelvin that are orange. White stars that have a temperature of 8,000 degrees are identified with the letter F. Stars with the spectral class of G are 6000 Kelvin and either white or blue. The final 2 letters, K and M, both include stars that are blue, but stars in the spectral class of K are 4000 Kelvin while stars in the spectral class of M are 3000 Kelvin. When looking at the Hertzsprung-Russell Diagram, the way the spectral class bar is arranged may be confusing since the temperature goes from highest on the left-hand side of the x-axis to lowest on the