Classifying Stars
2 marks · Easy| Star | Surface temperature (K) | Apparent colour |
|---|---|---|
| X | 6500 | yellow |
| Y | 4000 | red |
| Z | 32000 | blue |
Which star in the table is classified as type O and which as type M? Explain your choices.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
Z is O; Y is M. O stars are very hot and blue, M stars are cool and red.
Also accept: Star Z is O because it is hot and blue, Y is M because it is cool and red.
Common mistakes: Confusing the colour-temperature relationship; Assigning O to Y
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Correctly identifies Z as type O star and Y as type M star.
B2 · 1 mark · Provides a valid reason linked to temperature and colour for each.
Worked solution
Star Z has a temperature of 32,000 K and is blue, which matches O class (hottest, blue). Star Y is 4000 K and red, which matches M class (coolest, red).