Demolished Planets

Young star systems are dangerous places. A planet can be pelted by giant asteroids and comets. It can collide with its siblings, and be kicked out of the system by close encounters with other siblings. It might even be swallowed by its parent star. Astronomers in the U.K. recently found evidence of such encounters in several young stars. The researchers zeroed in on stars in three clusters. All of the clusters are young – from about 40 million to 200 million years old. At that age, their star systems might still be chaotic – planets might be getting blasted or destroyed, and they might still be taking shape. Six stars in the clusters showed especially high amounts of lithium. It’s a common planet-building material. But it’s fragile – stars quickly destroy it. So any lithium in the stars must have been added recently. The most likely source is young, rocky planets. The planets could have been kicked inward by the gravity of other planets, or dragged in by gas and dust around the stars. Over time, the remains churn deep into a star’s interior. But some can linger for a few million years – the remains of dead planets. One of the clusters is Blanco 1. It’s 850 light-years away, in the constellation Sculptor. It climbs into the southeast in mid evening, to the lower left of the bright star Fomalhaut. It’s too faint to see with the eye alone, but it’s a decent target for small telescopes. Script by Damond Benningfield