Hertzsprung-Russell diagram and stellar life cyclesEdexcel A-Level Physics: Flashcards

What these 13 flashcards ask

What does an HR diagram plot?
How is the temperature axis arranged on an HR diagram?
Where on the HR diagram are main-sequence stars?
Where are red giants on the HR diagram?
Where are white dwarfs on the HR diagram?
What happens in the core of a main-sequence star?
What balances gravity in a main-sequence star?
What forms a protostar?
How does a star become a red giant?
What is a planetary nebula?
What is the end state of a low-mass star?
How does the end of a massive star differ from the Sun's?
Why do massive stars have shorter lives?

Exam questions on Hertzsprung-Russell diagram and stellar life cycles

A star, R, has a surface temperature of 3200 K and a luminosity 5.0 × 10² times that of the Sun. Astronomers plot its position on a Hertzsprung-Russell (HR) diagram, which shows luminosity against surface temperature.
Explain why star R is much more luminous than the Sun even though its surface temperature is lower.2 marks
A cloud of cold gas and dust in space collapses and forms a star similar to the Sun, which then spends most of its life fusing hydrogen in its core.
Explain why the star stays at a constant size and luminosity for most of its life.2 marks
A white dwarf has a surface temperature of 12 000 K and a luminosity 1.0 × 10⁻³ times that of the Sun. The luminosity of the Sun is 3.85 × 10²⁶ W.
Calculate the radius of the white dwarf.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).