Collision Zones

Planetary systems can be dangerous. Like race cars zipping around a track, planets can ram into each other. That can destroy one or both of the planets, and create massive piles of debris. Some of that debris may then fall onto the parent star.

Astronomers have seen the likely aftermath of several such collisions. The most recent is in a star system in Auriga. The charioteer climbs into view in the northeast by about 10 p.m. It’s marked by the bright star Capella.

Astronomers have been intrigued by a star system known as RW Aurigae for decades. It consists of two stars in a tight orbit around each other. They’re only a few million years old.

The system periodically gets much fainter. In 2011, for example, it faded for about six months. It faded again in 2014, and stayed faint for more than two years.

A recent study says the dimmer switch probably was flipped by a collision between two small planetary bodies. The impact created a big cloud of dust and gas. The cloud passed in front of the star, blocking some of its light. And some of that material appears to be falling onto the star.

Such a discovery isn’t surprising. There’s evidence that young stars gobble up some of their close planets. Eventually, though, the systems calm down. Yet even then, collisions between planets and smaller bodies happen all the time — maintaining the danger level. We’ll have more about that tomorrow.

Script by Damond Benningfield