| Date | November 2014 | Marks available | 2 | Reference code | 14N.3.SL.TZ0.15 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | Describe | Question number | 15 | Adapted from | N/A |
Question
This question is about stellar radiation and stellar types.
Alnilam and Bellatrix are two stars in the constellation of Orion. The table gives information on each of these stars. \({L_ \odot }\) is the luminosity of the Sun and \({R_ \odot }\) is the radius of the Sun.
Using a telescope based on Earth, an observer estimates the distance to Alnilam using the stellar parallax method.
Describe the stellar parallax method.
Markscheme
the position of the star (relative to the fixed background) is measured six months apart/January to July;
the parallax angle p can be used to determine the distance using d = \(\frac{1}{p}\);
Examiners report
(b)(i) was mostly well answered.
