| Date | November 2015 | Marks available | 2 | Reference code | 15N.3.HL.TZ0.2 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | Describe | Question number | 2 | Adapted from | N/A |
Question
This question is about the Hertzsprung–Russell (HR) diagram and the Sun.
A Hertzsprung–Russell (HR) diagram is shown.
The Sun will remain on the main sequence of the HR diagram for about another five billion years. After this time it will become a red giant, following the evolutionary path shown in the diagram.
Outline why the Sun will leave the main sequence, and describe the nuclear processes that occur as it becomes a red giant.
Describe two physical changes that the Sun will undergo as it enters the red giant stage.
Markscheme
insufficient hydrogen (to continue fusion);
star collapses (under gravity);
temperature increases;
initiated fusion of helium, (energy released causes) rapid expansion of star;
rapid expansion / increase of size;
decrease in temperature / cooler stars appear red in colour / increase of luminosity;
Examiners report
Well-prepared candidates (both HL and SL) only had a problem with the part related to the use of a non-linear temperature scale. Average prepared candidates displayed difficulty in the experimental measurement of the temperature of the distant star and also with details of nuclear processes occurring in the Sun during transformation to a red giant.
Well-prepared candidates (both HL and SL) only had a problem with the part related to the use of a non-linear temperature scale. Average prepared candidates displayed difficulty in the experimental measurement of the temperature of the distant star and also with details of nuclear processes occurring in the Sun during transformation to a red giant.
