6.2.2. Stars
A subsection of Physics, 5054, through 6. Space physics
Listing 10 of 10 questions
Astronomical distances are measured in light-years. State what is meant by ‘a light-year’. The Sun is one star in the Milky Way galaxy. State the approximate diameter of the Milky Way galaxy. diameter of Milky Way = light-years There are several stages in the life cycle of a star. Complete to show the stages that a massive star goes through after it has used up most of the hydrogen at the centre of the star. Use words from the following list: nebula neutron star protostar red giant supernova white dwarf massive star (much larger than our Sun) red supergiant and black hole or State the stage in the life cycle of a star where heavy elements are formed. Question 10 continues over the page. Current scientific understanding is that the universe began 14 billion years ago in an event known as the Big Bang. Explain one observation that supports the Big Bang Theory. observation explanation
5054_s23_qp_22
THEORY
2023
Paper 2, Variant 2
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is a picture of a nebula formed from a supernova. State what is meant by ‘a supernova’. Describe how a protostar forms inside a nebula. Our Sun is in a circular orbit around a black hole at the centre of our galaxy. State the name of the galaxy that contains our Sun. State what is meant by a light-year. The time taken for one complete orbit of our Sun around the black hole is 7.3 × 1015 s. The distance from our Sun to the black hole is 26 000 light-years. 1 year = 3.2 × 107 s speed of light = 3.0 × 108 m / s Calculate the speed of our Sun as it orbits the black hole. Show your working and give your answer in m / s. speed = m / s
5054_s24_qp_22
THEORY
2024
Paper 2, Variant 2
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Stars that are being formed emit infra-red radiation. Some of this radiation is received by a telescope that orbits the Earth. Microwave signals from the telescope are sent to the Earth’s surface, as shown in . Microwaves travel at a speed of 300 000 km/s. The telescope is 600 km above the Earth’s surface. Calculate the time for a microwave signal from the telescope to reach the Earth’s surface. Infra-red and microwave radiation are both part of the electromagnetic spectrum. State two other similarities and give one difference between infra-red and microwave radiation. As clouds of gas and dust come together to form a star, there is an energy change similar to the energy change as a ball falls to the ground. The temperature in the clouds of dust and gas becomes so high that nuclear fusion occurs. In one such reaction, two isotopes of hydrogen, 2 1H and 3 1H, fuse together. Explain why the gas and dust come together. State the energy change that causes the rise in temperature as the gas and dust come together. Explain why high temperatures are needed for nuclear fusion to occur. Describe the structure of a nucleus of 3 1H. State which element is created by the fusion of two hydrogen nuclei. State one effect of nuclear fusion on a star. Earth microwaves telescope infra-red radiation distant star not to scale
5054_w06_qp_2
THEORY
2006
Paper 2, Variant 0
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In space, an interstellar cloud of dust and gas collapses to form a protostar. The cloud contains hydrogen. Describe the energy transfers that take place as the cloud collapses and forms the protostar. The collapse results in a nuclear reaction in the protostar that involves the isotope hydrogen-3 (3 1H). The isotope hydrogen-3 (3 1H) is radioactive. It decays by beta particle emission. State how the nuclei of isotopes of the same element are different. Explain why hydrogen-3 cannot decay by alpha particle emission. Complete the equation for the decay of hydrogen-3 to an isotope of helium (He). 1H β + He Explain how the nuclear reaction in the protostar stops further collapse as the protostar becomes a stable star. The cloud of dust and gas that collapses also contains atoms of the heaviest elements. State which part of the life cycle of a star is responsible for the production of the heaviest elements.
5054_w23_qp_22
THEORY
2023
Paper 2, Variant 2
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A stable star in a distant galaxy has a mass that is more than 15 times the mass of the Sun. State the name of the nuclear reaction that occurs at the centre of the star and describe this nuclear reaction. Explain how this nuclear reaction helps to keep the star stable. As a massive star approaches the end of its life, it stops being stable and becomes a red supergiant. State why the nuclear reaction can no longer keep the star stable. Describe what then happens to the red supergiant.
5054_w24_qp_21
THEORY
2024
Paper 2, Variant 1
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Questions Discovered
10