Astronomers have discovered that a Sun-like star lurking around 350 light-years away consumed the rocky equivalent of 15 Earths. Dubbed Kronos after the child-eating Titan of Greek mythology, the star is the clearest and most dramatic case yet of a Sun-like star consuming its own planets, said Semyeong Oh, astrophysicist at Princeton University in New Jersey and lead author of the study. “Even if our Sun ate the entire inner solar system, it wouldn’t come close to the anomaly we see in this star,” study co-author David Hogg from the Flatiron Institute in New York added. The research did not begin as a hunt for a planet-eater. Oh was analysing a catalog of new star data collected by the European Space Agency’s Gaia spacecraft for pairs of stars with similar speeds and trajectories. Such duos are typically twin stars that formed close together from the same ingredients. The analysis ultimately led to the identification of Kronos and its lesser known brother Krios. Their official designations are HD 240430 and HD 240429, and they are both about 350 light years from Earth.
The keys to the discovery were first confirming that the widely separated pair are in fact a binary pair, and secondly observing Kronos’ strikingly unusual chemical abundance pattern, Oh explained in a statement released by the Princeton University. Other co-moving star pairs have had different chemistries, Oh explained, but none as dramatic as Kronos and Krios.
Most stars that are as metal-rich as Kronos “have all the other elements enhanced at a similar level,” she said, “whereas Kronos has volatile elements suppressed, which makes it really weird in the general context of stellar abundance patterns.”
In other words, Kronos had an unusually high level of rock-forming minerals, including magnesium, aluminium, silicon, iron, chromium and yttrium, without an equally high level of volatile compounds — those that are most often found in gas form, like oxygen, carbon, nitrogen and potassium, the study said.