AQA A Level Physics Paper 3 Section B: Astrophysics June 2023 question paper 7408/3BA

Draw a labelled diagram to define the parsec (pc).

Table 1 shows data for two stars: Rigel and the Sun.

State the spectral class of Rigel.

The apparent magnitude of Rigel is 0.11

Calculate, in pc, the distance from Rigel to the Earth.

Figure 1 shows a Hertzsprung–Russell (HR) diagram.

Draw a line on Figure 1 to show the evolution of the Sun from formation to white dwarf.

One stage in the evolution of Rigel includes the emission of a gamma ray burst.

Outline the circumstances during which a gamma ray burst will be emitted by Rigel.

State what is meant by normal adjustment when applied to an astronomical refracting telescope.

Which combination of lenses gives the largest angular magnification when used as

V1031 and WASP-82 are two stars in the constellation Orion. V1031 appears 40 times brighter than WASP-82 when viewed from Earth. The apparent magnitude of V 1031 is 6.0

Calculate the apparent magnitude of WASP-82.

V1031 is just visible to the naked eye of an astronomer when her pupil diameter is 7 mm.

Suggest whether she can observe WASP-82 using a telescope with an objective diameter of 60 mm. Support your answer with a calculation.

CCDs are often connected to telescopes.

Explain two reasons why this improves the ability of astronomers to observe dim stars.

State the defining property of a black hole.

In 2019, astronomers linked several radio telescopes to produce a single telescope called the EHT. The resolution of the EHT is the same as the resolution that a telescope with an aperture equal to the diameter of the Earth could achieve.

Table 2 shows data about the EHT and the Hubble telescope.

Galaxy M87 is 5.3 × 10⁷ light years from Earth. The supermassive black hole at the centre of M87 has a mass 6.5 × 10⁹ times the mass of the Sun.

The radius of the event horizon is R.

The astronomers propose to use either the EHT or the Hubble telescope to observe stars whose distance from the centre of the black hole is less than 1000 R.

Discuss, with calculations, which telescope is more suitable for this observation.

A star is orbiting the black hole in M87. The star is observed in the plane of its orbit. The wavelength of a spectral line observed in the light emitted from the star varies between a maximum and a minimum value.

maximum value observed = 374.96 nm minimum value observed = 373.53 nm

Calculate the orbital speed of the star.

M40 A and M40 B are two stars that appear very close to each other when viewed from Earth. There are two possible reasons for this:

• they are an orbiting binary system

• they are distant from each other and only appear in the same line of sight.

In an orbiting binary system, the difference between the apparent magnitude and the absolute magnitude for each star is similar.

Table 3 shows data about these two stars.

Discuss the appearance of the two stars to an astronomer on the Earth. In your answer you should:

• compare the colour of the stars

• compare the brightness of the stars

• deduce, with a calculation, whether the stars form an orbiting binary system.

Figure 2 shows, for some galaxies, how their recession speed v varies with distance d from the Earth.

Estimate, using Figure 2, the age in seconds of the Universe.

The estimate in Question 05.1 assumes that the Universe has expanded at a constant rate. Measurements involving type 1a supernovae that are at large distances from Earth caused astronomers to make a modification to this assumption.

State:

• the modification

• the explanation that was proposed to account for this modification.