Star Evolution

How did the main sequence get its name?

The main sequence is the most prominent feature in an astronomical diagnostic tool called the Hertzsprung-Russell diagram. When astronomers want to study a population of stars, they measure the luminosity (or flux) and the temperature (or color) of each star, and plot the results on a diagram. Ejnar Hertzsprung (1873–1967) and Henry Norris Russell (1877–1957) were the first to make this kind of diagram, showing that the vast majority of data points fall in a narrow, diagonal zone in the diagram—a “main sequence.”


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