A. Space, time and motion

A.1 Kinematics

A.2 Forces and momentum

A.3 Work, energy and power

A.4 Rigid body mechanics

A.5 Galilean and special relativity

B. The particulate nature of matter

B.1 Thermal energy transfers

B.2 Greenhouse effect

B.3 Gas laws

B.4 Thermodynamics

B.5 Current and circuits

C. Wave behaviour

C.1 Simple harmonic motion

C.2 Wave model

C.3 Wave phenomena

C.4 Standing waves and resonance

C.5 Doppler effect

D. Fields

D.1 Gravitational fields

D.2 Electric and magnetic fields

D.3 Motion in electromagnetic fields

D.4 Induction

E. Nuclear and quantum physics

E.1 Structure of the atom

E.2 Quantum physics

E.3 Radioactive decay

E.4 Fission

E.5 Fusion and stars

S Skills in Physics

S1.1 Experimental techniques

S1.2 Technology

S1.3 Mathematics

S2.1 Exploring and designing

S2.2 Collecting and processing data

S2.3 Concluding and evaluating

IB Physics HL E.5 Fusion and stars Question Bank

[Maximum number: 5]

This question is about stars.

The Hertzsprung-Russell (HR) diagram shows the position of the Sun and three stars labelled A, B and C .

(a)

State the star type for A, B and C.

A:
B:
C:

[ 3 ]

(b)

Determine the ratio $\frac{\text { radius of } \mathrm{B}}{\text { radius of } \mathrm{A}}$ .

[ 2 ]

[Maximum number: 8]

This question is about stars in the constellation Canis Minor.

(a)

Luyten's star and Gomeisa are two stars associated with the constellation Canis Minor. The table gives data for these stars and for the Sun.

[ 3 ]

(i)

Explain, with reference to magnitude data from the table, why it is possible to use the stellar parallax technique to determine the distance of Luyten's star from Earth.

[ 3 ]

(b)

(i)

Gomeisa has a radius four times that of the Sun. Use the data in (c) to show that the ratio

\frac{\text { luminosity of Gomeisa }}{\text { luminosity of Sun }}

is about 200 .

[ 3 ]

(c)

Gomeisa, Luyten's star and the Sun are main sequence stars. On the grid of the Hertzsprung-Russell (HR) diagram, identify the position of

[ 1 ]

(i)

Luyten's star, with the letter L .

[ 1 ]

(d)

On the HR diagram above, sketch the likely evolutionary path of Luyten's star.

[ 1 ]

[Maximum number: 2]

This question is about determining the distance to a nearby star.

Two photographs of the night sky are taken, one six months after the other. When the photographs are compared, one star appears to have shifted from position A to position B, relative to the other stars.

(a)

Outline why the star appears to have shifted from position A to position B.

[ 1 ]

(b)

The observed angular displacement of the star is $\theta$ and the diameter of the Earth's orbit is d. The distance from the Earth to the star is D.

[ 1 ]

(i)

Draw a diagram showing d, D and $\theta$ .

[ 1 ]

[Maximum number: 2]

This question is about objects in the universe.

(a)

State one difference between

[ 1 ]

(i)

a main sequence star and a planet.

[ 1 ]

(b)

State how

[ 1 ]

(i)

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

[ 1 ]

(a)

Betelgeuse in the constellation of Orion is a red supergiant star.

[ 5 ]

(i)

Compare the fate of Aldebaran to that of Betelgeuse.
Aldebaran:
Betelgeuse:

[ 2 ]

(ii)

Outline, with reference to the Chandrasekhar limit, the circumstances under which the final state of Betelgeuse could be the same as the final state of Aldebaran.

[ 3 ]

[Maximum number: 5]

This question is about a particular star called Barnard's star.

The peak wavelength in the spectrum of Barnard's star is 940 nm . The following data are available.

\begin{array}{r} \frac{\text { apparent brightness of Barnard's star }}{\text { apparent brightness of the Sun }}=2.5 \times 10^{-14} \\ \frac{\text { luminosity of Barnard's star }}{\text { luminosity of the Sun }}=3.8 \times 10^{-3} \end{array}

(a)

(i)

Suggest why Barnard's star is not likely to be either a white dwarf or a red giant.

[ 2 ]

(b)

(i)

Outline how the parallax angle is measured.

[ 3 ]

[Maximum number: 8]

This question is about the life history of stars.

(a)

Outline, with reference to pressure, how a star on the main sequence maintains its stability.

[ 3 ]

(b)

A star with a mass equal to that of the Sun moves off the main sequence. Outline the main processes of nucleosynthesis that occur in the core of this star before and after this change.

[ 2 ]

(c)

Compare the fate of the star in (b) with that of a star of much greater mass.

[ 3 ]

[Maximum number: 4]

E2. This question is about the properties of a star.
(a) The peak in the radiation spectrum of a star X is at a wavelength of 300 nm .

Show that the surface temperature of star X is about 10000 K .
(b) (i) The radius of star X is $4.5 R_{\mathrm{S}}$ where $R_{\mathrm{S}}$ is the radius of the Sun. The surface temperature of the Sun is $5.7 \times 10^{3} \mathrm{~K}$ .

Determine the ratio $\frac{\text { luminosity of star } \mathrm{X}}{\text { luminosity of the } \mathrm{Sun}}$ .
(ii) Calculate, assuming that the power in the mass-luminosity relationship is 3.5 , the ratio $\frac{\text { mass of star X }}{\text { mass of Sun }}$ .
(c) On the Hertzsprung-Russell diagram, label
(i) the position of star X with the letter X .
(ii) the position of the Sun with the letter S .

(d) Explain, with reference to the Chandrasekhar limit, whether or not star X will become a white dwarf.

[Maximum number: 4]

E3. This question is about stellar evolution.
In the HR diagram below, the Sun and another main sequence star, X , have been marked.

(a) (i) On the diagram above, draw a line to show the evolutionary path of the Sun from its present position on the main sequence to the final stage in its evolution.
(ii) Explain, by reference to the Chandrasekhar limit, why the final stage in the evolution of the Sun is the one you indicated in (a)(i).
(b) (i) Show that the mass of star X is approximately 14 solar masses. (Assume that n=3.5 in the mass-luminosity relation.)
(ii) State the likely final stage of star X .

[Maximum number: 5]

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.

(a)

Using a telescope based on Earth, an observer estimates the distance to Alnilam using the stellar parallax method.

[ 5 ]

(i)

Describe the stellar parallax method.

[ 2 ]

(ii)

Determine whether the stellar parallax method can be used to estimate the distance of Alnilam from Earth.

[ 3 ]

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Question 1(a)

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Question E1

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Question 2

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