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Date May 2014 Marks available 2 Reference code 14M.3.SL.TZ2.12
Level Standard level Paper Paper 3 Time zone Time zone 2
Command term Calculate Question number 12 Adapted from N/A

Question

This question is about objects in the universe.

State one difference between

(i)     a main sequence star and a planet.

(ii)     a stellar cluster and a constellation.

[2]
a.

State how

(i)     it is known that main sequence stars are made predominantly of hydrogen.

(ii)     a main sequence star remains in equilibrium despite it having a great mass.

[2]
b.

The graph shows the variation with wavelength of the intensity of a main sequence star.

M14/4/PHYSI/SP3/ENG/TZ2/12.c

Calculate the surface temperature of this star.

[2]
c.

Markscheme

(i) stars, and not planets, have cores undergoing fusion;

stars have much greater mass/luminosity/absolute magnitude/temperature than planets;

planets reflect starlight rather than emit;

planets in our solar system can show retrograde motion, stars cannot;

Allow other sensible answers.

(ii) stars in a stellar cluster are close to each other/kept together by gravitation, the stars in a constellation are not;

a.

(i)     the lines in the (absorption) spectrum of the star (correspond to hydrogen wavelengths);

(ii)     the gravitational force that tends to collapse the star is balanced by a force due to radiation pressure;

b.

peak wavelength is at 400 (nm); (accept answers in the range of 380 to 420 (nm))

\(T = \left( {\frac{{{\text{2.9}} \times {\text{1}}{{\text{0}}^{ - 3}}}}{{{\text{400}} \times {\text{1}}{{\text{0}}^{ - 9}}}} = } \right){\text{ 7250 (K)}}\); (accept answers in the range of 6900 to 7600 (K))

Award [2] for a bald correct answer.

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Option D: Astrophysics » Option D: Astrophysics (Core topics) » D.2 – Stellar characteristics and stellar evolution
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