| Date | November 2017 | Marks available | 2 | Reference code | 17N.3.SL.TZ0.11 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | Show that | Question number | 11 | Adapted from | N/A |
Question
Two of the brightest objects in the night sky are the planet Jupiter and the star Vega.
The light observed from Jupiter has a similar brightness to that received from Vega.
Vega is found in the constellation Lyra. The stellar parallax angle of Vega is about 0.13 arc sec.
Identify the mechanism leading stars to produce the light they emit.
Outline why the light detected from Jupiter and Vega have a similar brightness, according to an observer on Earth.
Outline what is meant by a constellation.
Outline how the stellar parallax angle is measured.
Show that the distance to Vega from Earth is about 25 ly.
Markscheme
«nuclear» fusion
Do not accept “burning’’
brightness depends on luminosity and distance/b = \(\frac{L}{{4\pi {d^2}}}\)
Vega is much further away but has a larger luminosity
Accept answer in terms of Jupiter for MP2
a group of stars forming a pattern on the sky AND not necessarily close in distance to each other
OWTTE
the star’s position is observed at two times, six months apart, relative to distant stars
parallax angle is half the angle of shift
Answers may be given in diagram form, so allow the marking points if clearly drawn
\(\frac{1}{{0.13}}\) = 7.7 «pc»
so d = 7.7 x 3.26 = 25.1 «ly»
