AGEING ungrac efully

As stars grow older, they and their planets can affect each other in strange and violent ways.

by Melinda Soares-Furtado

ASTRONOMERS HAVE CONFIRMED the existence of more than 5,000 exoplanets to date. The vast majority of these — approximately 95% — orbit stars in an evolutionary stage akin to that of our Sun, a stage known as the main sequence. Main-sequence stars actively fuse hydrogen into helium in their dense, hot cores. Stars spend the vast majority of their nuclear-burning lives in this stage: In the case of a Sun-like star, the main sequence comprises 90% of the total stellar life cycle. But what about the 5% of known exoplanets found around aging stars? These stars bear exotic names like subgiants, red giants and white dwarfs, and they have evolved to have vastly different sizes, temperatures and luminosities than they did when they were young. Any planets around these stars have…

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Australian Sky & Telescope (Digital) - 1 Issue, March 2023

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