The Hertzsprung-Russell Diagram: Early 20th Century

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Hertzsprung-Russell Diagram, a 2D diagram designed to plot temperature against luminosity and colour against absolute magnitude. Find out how this magnificent figure was invented during the early 20th century. – Ryota Kusumoto
The Hertzsprung-Russell Diagram (also known as the HR Diagram) is one of the most important tools in the study of stellar evolution. It was developed individually by 2 scientists, Ejnar Hertzsprung and Henry Norris Russel. The diagram made in the 1900’s, it plots the temperature of stars against luminosity or the colour of stars against absolute magnitude. To read the HR diagram there are several parts that need to be understood. In the middle stretching from the upper left to the bottom right is the Main Sequence stars where most normal stars including our sun occur. They range from hot and luminous (Upper left) to cool and faint (Lower right). These stars spend 90% of their lives burning hydrogen and helium in their cores. At the top right are the brightest stars called Supergiants and going down are the Red Giant. These stars have …show more content…

The first design originated in 1911 with Danish astronomer, Ejnar Hertzsprung plotted the absolute magnitude of stars against their colour. The second design originated in 1913 when American Astronomer Henry Norris Russel plotted spectral class against absolute magnitude. Their results showed a relationship between the temperature and luminosity and showed that they were not random but in fact fell in distinct groups. Depending on its starting mass, every star goes through the evolutionary stages dictated by its internal structure and how it produces energy. Each of the stages correspond to a change in temperature or luminosity which then changes the position of the star located on the HR diagram. Therefore astronomers can now know a star’s internal structure and which stage it’s at by locating the position of where the star lies on the

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