вЂњStars take millions or even billions of years to evolve,вЂќ Dr Campbell says. Oxygen, carbon and nitrogen were among the elements made by the first stars вЂ“ theyвЂ™re also necessary for life on Earth. They then found their way into the next generation of stars. In this way the new elements produced by dying stars slowly populated the interstellar medium вЂ“ or the space between the stars. вЂњThese first stars formed, they exploded, or they were more like the sun and they blew off their wings, and this polluted вЂ“ or maybe I should say enriched вЂ“ the universe,вЂќ Dr Campbell says. When stars end their lives, the elements within them fuse to form new elements. According to astronomical research published just last year, stars first appeared about 180 million years after the Big Bang. вЂњYou couldnвЂ™t have planets, you couldnвЂ™t have life at that stage,вЂќ Dr Campbell says. The first stars were composed of the first three elements in the table вЂ“ hydrogen, helium and a small amount of lithium. Each generation of stars is more complex than the stars that preceded it, Dr Campbell explains. Stars have been evolving from the Big Bang onwards. The study found that the stars were dying prematurely, upending ideas about stellar evolution. Dr Campbell took part in a 2016 study in which HERMES examined some ancient stars in a globular cluster called M4. The Anglo-Australian ObservatoryвЂ™s HERMES spectrograph, for example, can analyse the chemical composition of 400 stars at a time. Our understanding of how the stars produced the elements is changing, as the instruments we use to interrogate the stars becomes more sophisticated. Jennifer Johnson, the tableвЂ™s author, first compiled it in 2017, but says itвЂ™s a work in progress, as new research gives more accurate information about the role stars have played. The table shows which elements were produced by the Big Bang, which were produced by exploding massive stars (supernovae), or dying low-mass stars or merging neutron stars, for instance. On his laptop, he calls up a colour-coded periodic table, entitled a вЂњ chemical history of the universe вЂќ. One of Dr CampbellвЂ™s interests is how the elements were made. Yet we tend not to think about the stars very much, or even notice them. All the elements in the periodic table originated in the stars.

Life on Earth wouldnвЂ™t be possible without them. Most people donвЂ™t realise that stars are the reason we exist, he says. So he studied them instead вЂ“ and became an astrophysicist. Philosophy and psychology were two possibilities, but the night stars made him curious.ДЄll the elements in the periodic table came from the stars. He was still a teenager, trying to decide what subjects to pursue at university. The stars spoke to Simon Campbell when he was camping at Wye River, on a surfing holiday.

Towards the stars