For those interested in the long-term outcome of our solar system and in particular its sun, our sun, this is an interesting read from Quanta about how the metal content of the sun – even in fractions of a percent – may have an effect on the lifespan of that ball of fire in space.
Like any star in its prime, the sun consists mainly of hydrogen atoms fusing two by two into helium, unleashing immense energy in the process. But it’s the sun’s tiny concentration of heavier elements, which astronomers call metals, that controls its fate. “Even a very small fraction of metals is sufficient to alter the behavior of a star completely,” explained Sunny Vagnozzi, a physicist at Stockholm University in Sweden who studies the “metallicity” of the sun. The more metallic a star, the more opaque it is (since metals absorb radiation), and how opaque it is in turn relates to its size, temperature, brightness, life span and other key properties. “Metallicity basically also tells you how the star will die,” Vagnozzi said.
But the sun’s metallicity, beyond revealing its own story, also serves as a kind of yardstick for calibrating measurements of the metallicity of all other stars, and thus the ages, temperatures and other properties of stars, galaxies and everything else. “If we change the solar yardstick, automatically it means that our understanding of the cosmos has to change,” said Martin Asplund, an astrophysicist at Australian National University. “So having an accurate knowledge of the solar chemical composition is extremely important.”