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An introduction to the hertzsprung russell diagram and the way it works

Stars and the Hertzsprung-Russell Diagram Teacher Sheet Introduction These are some suggested answers for the questions asked on the student sheet.

Luminosity and temperature Describe why it is possible to relate the temperature of a star to its luminosity, or brightness. Stars that are hotter should be brighter than stars that are cooler. Why is measuring the luminosity of stars difficult? The distance of stars relative to earth makes it difficult to measure brightness since a bright star that is more distant might appear to be as bright as a more dim star closer to earth.

What star serves as a standard of comparison against which the luminosity of other stars is measured? Sketch and label the HR Diagram. Make sure to label the axes, the main sequence, white dwarves, giants, and super giants. Students should sketch the HR Diagram, from the website: The class of star that corresponds to the color we observe from earth. What are the four important things to note about the HR Diagram?

  1. Also plotted are the Morgan-Keenan luminosity classes that distinguish between stars of the same temperature but different luminosity.
  2. The sun is a Main Sequence star.
  3. They have low surface temperatures and high luminosities which, according to the Stefan-Boltzmann law, means they also have large radii. Main sequence stars have a Morgan-Keenan luminosity class labelled V.
  4. Star C is also a hot, blue star. Star A is red and therefore, cool.

Are blue stars hotter or cooler than red stars? If a star has a luminosity of ten thousand 10,how many times brighter is it than the sun? How does the brightness of white dwarfs relate to that of the sun?

Stars and the Hertzsprung-Russell Diagram Teacher Sheet

White dwarfs are less bright than the sun. Part Two Describe the general trend between temperature and luminosity that the Main Sequence shows. A hotter star should be brighter than a cooler star. Why do giants differ from stars in the Main Sequence?

Hertzsprung-Russell Diagram

Although they are cool [red], they are very luminous, and therefore bright. In the Main Sequence, stars that are cool are not as luminous.

  • The giant branch and supergiant stars lie above the main sequence, and white dwarfs are found below it;
  • Main sequence stars have a Morgan-Keenan luminosity class labelled V;
  • This teacher sheet is a part of the How Old Are the Stars?
  • The HR Diagram tells us the luminosity of the sun.

How do white dwarf stars differ from stars in the Main Sequence? White dwarf stars are very hot [blue], but dim because they are so small. Star A is red and therefore, cool. Star B is a hot, blue star and very luminous. Both A and B are on the Main Sequence.

  1. This Hertzsprung-Russell diagram shows a group of stars in various stages of their evolution. Developed independently in the early 1900s by Ejnar Hertzsprung and Henry Norris Russell, it plots the temperature of stars against their luminosity the theoretical HR diagram , or the colour of stars or spectral type against their absolute magnitude the observational HR diagram, also known as a colour-magnitude diagram.
  2. Also plotted are the Morgan-Keenan luminosity classes that distinguish between stars of the same temperature but different luminosity. Stars and the Hertzsprung-Russell Diagram Teacher Sheet Introduction These are some suggested answers for the questions asked on the student sheet.
  3. What are the four important things to note about the HR Diagram?

Star C is also a hot, blue star. However, it is very dim and therefore off the Main Sequence. Star D is a cool, red star but very luminous; it is also off the Main Sequence. The sun is a Main Sequence star. The HR Diagram tells us the luminosity of the sun. Using this information and the HR Diagram, determine what the sun's class might be as a star.

  • Depending on its initial mass , every star goes through specific evolutionary stages dictated by its internal structure and how it produces energy;
  • The HR Diagram tells us the luminosity of the sun;
  • Stars and the Hertzsprung-Russell Diagram Teacher Sheet Introduction These are some suggested answers for the questions asked on the student sheet;
  • The giant branch is also well populated and there are many white dwarfs.

The sun is a G star. This teacher sheet is a part of the How Old Are the Stars? Did you find this resource helpful?