Hertzsprung–Russell (HR) diagrams have been an integral part of astronomy for over a hundred years. Stars at different stages of life occupy different parts of the diagram, which allows us to take in a population of stars at a glance. The Gaia mission provided us with an enormous sample of stars — what can we learn by putting them in a HR diagram?
Have You Heard About HR Diagrams?
A qualitative HR diagram showing where different types of stars live. The colors are roughly true to life. Temperature is given on the x-axis with luminosity or brightness on the y-axis. [ESO]HR diagrams are fairly simple — they’re just plots of stars’ brightness versus color. But it turns out that stars change drastically as they evolve, moving from one part of the HR diagram to another as they go through different stages of life. This means that if you wanted to learn the rough age of a star, you could just check where it lands on a HR diagram.
It’s also interesting to see where stars cluster on HR diagrams. Some parts of this plot will never be filled in because it’s physically impossible for stars to occupy those spaces. So, ...