Stellar Evolution
5 marks · NormalAn astronomer observes a distant galaxy and finds a star that is much more massive than the Sun. The star's surface temperature is 30,000 K, and it emits mostly blue light.
Using the star classification table, state the spectral class of this star and its likely colour.
Describe the final stages in the life of a star with much greater mass than the Sun, including possible remnants.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Class O or B; colour is blue.
(b) A massive star will end as a red supergiant, then explode in a supernova. It will leave behind a neutron star, or if the core is massive enough, a black hole.
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Marking points
B1 (a) · 1 mark · Identifies class O or B for a star with 30,000 K.
B2 (a) · 1 mark · States colour is blue.
B3 (b) · 1 mark · Describes expansion into a red supergiant.
B4 (b) · 1 mark · Describes supernova explosion.
B5 (b) · 1 mark · Mentions final remnant: neutron star or black hole.
Worked solution
a) A star with a surface temperature of 30,000 K and blue colour is class O or B.
b) A star much more massive than the Sun will expand to become a red supergiant, then explode as a supernova. The remnant core will become either a neutron star or, if massive enough, a black hole.