A Hertzsprung-Russell (H-R) Diagram is an important tool in astronomy. This diagram helps astronomers learn the age and distances of stars and star clusters, (pg 171, Lab Manual). Typically, an H-R Diagram plots Luminosity (y-axis) against Temperature and Spectral Type (x-axis) (this axis is also “backwards” meaning that temperature is higher on the left and lower on the right). In the upper left corner of the diagram, you would see hot luminous stars plotted there, and in the bottom right there would be cool, faint stars. There are also four different regions on the diagram that tell you what type of the stars dwell in that area (knowing what type/ stage the star is in may help astronomers determine the composition of the stars as well as their next evolutionary stage.) There is Region I (Supergiants), Region III (Giants), Region V, Dwarfs and then the Main Sequence.
To plot a star you would need to measure the Luminosity of the stars
…show more content…
This can be found using the Stefan-Boltzmann Law L = 4πR2 σT4 (L = Luminosity, R= radius, T = temperature). https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwj01JbkxdvSAhUURmMKHSewDJoQjRwIBw&url=http%3A%2F%2Fastro.unl.edu%2Fnaap%2Fhr%2Fhr_background3.html&psig=AFQjCNHW8EfafuUDrTF7VSm1NJN0x7WaeQ&ust=1489771511395096
Astronomers find the H-R diagram useful when tracking the evolution of stars and the chemical and physical properties of a star. Astronomers also use the H-R diagram to estimate the age of a plotted star cluster based on where the stars turn off the main sequence. If the main sequence turnoff is closer to the upper left corner of the H-R diagram the star cluster is still very young (at this point it may be that only the massive blue stars have turned off). If the turnoff point is closer to the lower right corner of the diagram the star cluster is very