Like the Greek god Chronos, a good number of stars devour their children. As many as one-third of them have swallowed one or more of their own planets, a new study suggests. The findings could help astronomers rule out stellar systems unlikely to contain Earth-like worlds. The team investigated how often this happens by looking at 107 binary systems containing two Sun-like stars -- akin to the fictional two-sunned world Tatooine in Star Wars. In 33 of these pairs, one of the companions showed elevated levels of iron compared with the other, a sign of planetary cannibalism. These same partners were also rich in lithium, giving further credence to the world-munching hypothesis. Although Sun-like stars are born with substantial amounts of lithium, they burn it away within the first 100 million years of their lives, so seeing it in the older stars in the study sample indicated it likely came from a planet. Using these different lines of evidence, the team was able to model that between 20% and 35% of Sun-like stars consume a few Earths' worth of their offspring. Such events could happen in systems where gravitational interactions among the planets would either fling one into the central star or bring it close enough for the star to slowly vaporize and devour it. The findings have been published in the journal Nature Astronomy.

 

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