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In 1957, the famous B2FH paper was published – so named based on the initials of its authors. Its title was ‘Synthesis of the Elements in Stars’, and provided some of the first astronomical data to support the idea of stellar nucleosynthesis: that nuclear fusion inside stars produces chemical elements. Name the first author of this paper, who also fought discrimination against women in astronomy.
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Stars, like the Sun, host nuclear fusion reactions that each release more energy than they consume. If an atom’s nucleus is bound together with some energy, and if it’s fused with another similar nucleus to produce a third nucleus that requires less binding energy, the ‘excess’ is released in the reaction. Name the element on the Periodic Table whose nucleus is the lightest for which fusion releases less energy than it consumes.
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Scientists have hypothesised that stars have two main fusion reactions by which they convert hydrogen to helium – the start of stellar nucleosynthesis. Of these, the proton-proton cycle starts at around 4 million K and the ___ cycle, at around 15 million K. Fill in the blank with the name of this cycle, which comes from its use of three elements as catalysts to convert hydrogen to helium.
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A star also produces elements when it ‘dies’ – especially if its mass is 8x to 50x as much as the Sun. In this process, the star’s core, which no longer has fuel to fuse, starts to collapse rapidly under the weight of its own gravity while its outer layers are blown away. This blow-away pushes a large number of neutrons through its surroundings, which smash into atoms and produce roughly half of all elements in the universe heavier than iron. What is this process called?
