15 Questions
What is the Hertzsprung-Russell diagram?
A plot that shows the relationship between temperature and luminosity of stars
What is the Hertzsprung-Russell diagram (H-R diagram)?
A diagram used in astrophysics to show the relationship between the temperature and luminosity of stars
What is the Main Sequence?
A region where most stars, including our Sun, are found on the H-R diagram
What are the three major groups of stars found on the H-R diagram?
Main sequence stars, giants, and white dwarfs
What are the giants and supergiants?
Luminous stars that have evolved off the main sequence
What can be inferred from the position of stars on the H-R diagram?
Their size
What is the Stefan-Boltzmann relationship?
A relationship between the energy emitted per unit surface area per second and the fourth power of temperature
What is the Stefan-Boltzmann relationship?
It explains that the more luminous a star is, the bigger it is
What is the difference between supergiants and other stars?
Supergiants have much higher luminosities due to their larger radii
What are the three groups of M-class stars?
Supergiants, giants, and dwarfs
What are white dwarfs?
Very hot stars that are extremely small, roughly the size of Earth
What are the characteristics of white dwarfs?
They are small and have a very low surface area
Why does Procyon B have a smaller surface area than Barnard star?
Because it is much hotter
Which axis of the H-R diagram displays the luminosity of stars?
The vertical axis
What are colour-magnitude diagrams?
Diagrams where V is plotted against colour index, B-V
Study Notes
The Hertzsprung-Russell diagram (H-R diagram) is a useful and powerful plot in astrophysics that shows the relationship between temperature and luminosity of stars, and groups stars into distinct categories based on their position on the diagram.
The majority of stars, including our Sun, are found along a region called the Main Sequence, where hotter stars are more luminous.
Other major groups of stars found on the H-R diagram are the giants and supergiants, luminous stars that have evolved off the main sequence, and the white dwarfs.
The Stefan-Boltzmann relationship explains that the more luminous a star is, the bigger it is, and the difference between different groups of M-class stars is a difference in size.
Supergiants have the same effective temperature as other stars but have much higher luminosities due to their larger radii.
White dwarfs are very hot but have a very low surface area, meaning they are extremely small, roughly the size of Earth.
The scales on the axes of the H-R diagram can be confusing, with effective temperature decreasing from left to right, the highest temperature being on the left-hand side.
The vertical axis of the H-R diagram displays the luminosity of stars, either as a ratio compared to the Sun or as absolute magnitude.
When plotting stars in a specific open or globular cluster, apparent magnitude or V may be used instead of absolute magnitude.
Diagrams where V is plotted against colour index, B-V, are also known as colour-magnitude diagrams.
Test your knowledge of the Hertzsprung-Russell diagram with our quiz! Explore the different groups of stars found on the diagram and learn about the Stefan-Boltzmann relationship. See if you can navigate the confusing scales on the axes and understand the difference between absolute and apparent magnitude. Challenge yourself with questions about plotting stars in specific clusters and interpreting colour-magnitude diagrams. Sharpen your astrophysics skills and become an expert on the H-R diagram with our quiz.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
