Hertzsprung-Russell Diagrams

Test yourself

Hertzsprung-Russell (HR) Diagrams

The Hertzsprung-Russel diagram (HR diagram) is a plot of luminosity against temperature.

Illustrative background for HR diagramIllustrative background for HR diagram ?? "content

HR diagram

  • Most stars have a position on the HR diagram.
  • On this diagram, the Sun is at a luminosity of 1 and is a G class star.
Illustrative background for VersionsIllustrative background for Versions ?? "content


  • There are different versions of the HR diagram, some of which use absolute magnitude instead of luminosity, others which use spectral class instead of temperature.
Illustrative background for Path through the HR diagramIllustrative background for Path through the HR diagram ?? "content

Path through the HR diagram

  • Stars similar to our Sun follow the path as shown on the diagram.
  • The Sun is currently at stage 3, on the Main Sequence.
Illustrative background for Path through the HR diagram 2Illustrative background for Path through the HR diagram 2 ?? "content

Path through the HR diagram 2

  • After this, at stage 4, it will be a red giant star.
  • Finally, at stage 5, it will become a white dwarf.
  • Prior to stage 3, the Sun was a protostar (stage 1) and then a T-Tauri star in its infancy at stage 2.

Jump to other topics

1Measurements & Errors

2Particles & Radiation


4Mechanics & Materials


6Further Mechanics & Thermal Physics (A2 only)

7Fields & Their Consequences (A2 only)

8Nuclear Physics (A2 only)

9Option: Astrophysics (A2 only)

10Option: Medical Physics (A2 only)

11Option: Engineering Physics (A2 only)

12Option: Turning Points in Physics (A2 only)

Go student ad image

Unlock your full potential with GoStudent tutoring

  • Affordable 1:1 tutoring from the comfort of your home

  • Tutors are matched to your specific learning needs

  • 30+ school subjects covered

Book a free trial lesson