Process of using Cepheid variables to determine distance
When measuring the distances of galaxies, autonomists use Cepheid variables. The brightness of these variables differs because of their varying distances. When measuring them, it is important to make a lot of observations on different nights. If their periods are observed, it will be possible for the astronomer to determine how bright they are. The periods obtained will be an essential set of data for this activity. After recording the findings, the information got should be formulated in a data curve to create room for the comparison of the intrinsic brightness of the variables. Thus, it will be so easy to determine the magnitude of these variables and eventually get the interstellar and intergalactic distances of the star.
Hertzsprung–Russell Diagram (HRD)
In astronomy, HRD refers to a graph that shows the relationship between the classifications, absolute magnitude and effective temperatures of stars. It helps in defining different types of stars and matches their predictions into stellar evolution through comparing its brightness, color and temperature. In order to achieve this role, an astronomer must compare the computer generated models to the actual stars observed. This diagram can have vertical or horizontal axes depending on its absolute magnitude. HRD is formed by the stars during the main sequence. When using it, the magnitude is plotted in the Y- axis while temperature is plotted on the X- axis in which hot and dim lights are located closest to the origin. However, protostars are located at the bottom right corner of this diagram. At the bottom right of these protostars, the astronomer should plot the main sequence which caries the plasma core with the hydrogen fusion processes around it. At the same time, all the stars located at the right of the main sequence are smaller because of their lower mass and temperature.