Fig. 1 shows a classroom card-sort activity. Each card names one stage in the life cycle of a star with a mass like the Sun. A student has put the cards in ...
Question 1 Report
Fig. 1 shows a classroom card-sort activity. Each card names one stage in the life cycle of a star with a mass like the Sun. A student has put the cards in an incorrect order. The cards describe the object after a cloud of gas and dust has collapsed. The teacher asks students to sketch a corrected sequence in their answer box. The final object is very small and hot at first, but no longer has fusion reactions taking place. It will cool over an extremely long time.
(a) Sketch the correct order of the four cards, starting with protostar. [2]
(b) What happens to a white dwarf over a very long time? [2]
Fig. 1 shows a simplified graph from an outreach article. It compares the mass of a star at birth with its possible final remnant. The boundaries are approximate because other factors can affect a real star. A student uses the graph to predict the future of a star with mass 12 solar masses. The star is already a red supergiant. It will not form a planetary nebula because its mass is too great. The graph shows that it must first release a very large amount of energy in an explosion.
(a) Which remnant is most likely for the 12 solar-mass star? [2]
(b) When does the supernova occur: before or after the red supergiant stage? [2]
Answer Details
Sun-like star sequence
(a) The correct order is:
protostar → main sequence → red giant → white dwarf. [2]
(b) A white dwarf cools over a very long time and eventually becomes a black dwarf. [2]
Massive-star remnant
(a) A star with a birth mass of 12 solar masses is most likely to form a neutron star. [2]
(b) The supernova occurs after the red supergiant stage. [2]
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