AQA A Level Physics Paper 3 Section B: Astrophysics November 2021 question paper 7408/3BA

Figure 1 shows the evolution of a star similar to the Sun on a Hertzsprung-Russell (HR) diagram.

State the evolutionary stage of the star at each of the points W, X, Y and Z.

Theta Carinae is a star with a radius five times that of the Sun. It has a surface temperature of 31 000 K.

Annotate Figure 1 with a T to show the position of Theta Carinae.

An astronomer suggests that an Earth-sized planet orbits Theta Carinae.

Explain one difficulty with using the transit method to detect this planet.

The astronomer suggests that the Earth-sized planet receives a similar amount of power from Theta Carinae as the Earth does from the Sun.

The average power output of the Sun is 3.8 × 10²⁶ W.

Determine the orbital radius of the Earth-sized planet orbiting Theta Carinae.

Which graph shows the light curve for a typical type 1 a supernova?

Tick () one box.

The Andromeda galaxy is approximately 7.7 × 10⁵ pc from Earth.

Deduce whether a type 1 a supernova which occurred in Andromeda can be observed from Earth with the naked eye.

Miaplacidus and Avior are two stars in the constellation Carina. Miaplacidus is a class A star. Avior is a class K star.

Figure 2 shows how the intensity of radiation arriving at the Earth varies with wavelength for one of these stars. Only the important features of the variation are shown.

Deduce, with reference to Figure 2, the identity of the star.

In your answer you should:

• explain the overall shape of the graph

• describe the processes in the star that lead to the decreases in intensity

• state the identity of the star.

IC 2497 is a galaxy that contained a quasar. It is believed that the quasar stopped emitting radiation several thousand years ago.

Suggest why the quasar stopped emitting radiation.

IC 2497 has a red shift of 0.0516

Determine the distance from the Earth to IC 2497. Give an appropriate unit for your answer.

Explain what is meant by the Rayleigh criterion.

A telescope uses wavelengths in the range 90 nm to 120 nm.

Explain why this telescope must be located in space.

Go on to discuss one advantage that this telescope has compared to a telescope with the same aperture that uses visible light.

Table 1 shows information about two telescopes.

Each telescope detects radio waves with a wavelength of 21 cm.

Compare the performances of the telescopes in Table 1 when both are used to observe the same faint radio objects.