Collision of planets could have caused dimming of star 450 light years away, MIT claims

Planetary collision might shed light on the chaotic processes behind a star's early development

Physicists from MIT have discovered that a collision of two infant planetary bodies could have caused the dimming of a star they've been observing that resides in the Taurus-Auriga constellation some 450 light years from Earth.

They concluded that planetary debris from the collision fell into the star, and as it did so, generated a dense cloud of gas and dust, which temporarily obscured the star's light and thus our view of it.

The star in question is the young RW Aur A, and it has been observed for some time via NASA's Chandra X-Ray Observatory because every few decades, the star's light has faded briefly before brightening again.

In recent years, astronomers have observed the star dimming more frequently, and for longer periods, which ultimately lead to the recent discovery of the collision. The astronomers believe these findings could shed light on some of the chaotic processes that take place early in a star's development.

"Computer simulations have long predicted that planets can fall into a young star, but we have never before observed that," said Hans Moritz Guenther from MIT's Kavli Institute for Astrophysics and Space Research, who led the study.

"If our interpretation of the data is correct, this would be the first time that we directly observe a young star devouring a planet or planets."

Guenther is the lead author of a paper detailing the group's results, which appears in the Astronomical Journal.

He explained that the star's previous dimming events may have been caused by similar smash-ups, of either two planetary bodies or large remnants of past collisions that met head-on and broke apart again.

"It's speculation, but if you have one collision of two pieces, it's likely that afterward, they may be on some rogue orbits, which increases the probability that they will hit something else again," he said.