Classification of Stars (AQA A Level Physics)

Table 2 gives data about the supergiant star Melnick 34 and the Sun.

Table 2

Calculate .

Discuss why the evolution of a supergiant star in the local part of our galaxy could be dangerous for life on Earth.

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

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

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

Table 1 summarises some information about four stars in the constellation Cassiopeia.

Table 1

Which star has the highest surface temperature?

Figure 1 shows the intensity received at Earth from two of the stars, plotted against wavelength.

The effect of absorption by the Earth’s atmosphere is not shown.

Figure 1

Discuss what information can be found from Figure 1 about the temperature and colour of these stars.

Support your answer with suitable calculations.

State which star in Table 1 is dimmest on the absolute magnitude scale.

Calculate the absolute magnitude of Schedar.

Tsih has a mass over 15 times the mass of the Sun.

Tsih may eventually collapse to form a black hole.

Calculate the radius of the event horizon for a black hole with a mass 15 times that of the Sun.

3C 273 was the first quasar to be discovered. IC 1101 is one of the largest galaxies known.

Table 2 shows some information about these objects.

Table 2

State the property of the quasar that led to its discovery.

Show that the absolute magnitude X of quasar 3C 273 is about −27

Assume that the quasar and the galaxy are both viewed from the same distance.

Explain which would be the brighter object.

Go on to calculate the ratio .

The black hole at the centre of IC 1101 has a mass of 7.1 × 10¹¹ where is the mass of the Sun.

Calculate the average density within the event horizon of the black hole.

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

Figure 1

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.