Scientists Detect Comets Outside our Solar System

A team of professional and citizen scientists identifies tails of comets streaking past a distant star.

Scientists Detect Comets Outside our Solar System
An artist’s conception of a view from within the Exocomet system KIC 3542116. Image: Danielle Futselaar

MIT scientists along with amateur astronomers have captured the dusty tails of six exocomets orbiting around a faint star 800 light years from Earth. These comets outside our solar system were about the size of Halley’s Comet and traveled about 100,000 miles per hour before they ultimately vaporized.

As scientists reported, these are some of the smallest objects yet found outside our own solar system. The discovery was made by using the transit photometry, a technique by which astronomers observe a star’s light for telltale dips in intensity. Here, scientists detected or trail of gas and dust.

Professor Saul Rappaport said, “It’s amazing that something several orders of magnitude smaller than the Earth can be detected just by the fact that it’s emitting a lot of debris. It’s pretty impressive to be able to see something so small, so far away.”

Scientists used data from NASA’s Kepler Space Telescope. To date, the mission has identified and confirmed more than 2,400 exoplanets, mostly orbiting stars in the constellation Cygnus.

Thomas Jacobs, an amateur astronomer said, “For me it is a form of treasure hunting, knowing that there is an interesting event waiting to be discovered. It is all about exploration and being on the hunt where few have traveled before.”

Jacobs wanted to search for single transits, meaning they are not periodic like planets orbiting a star multiple times. During the search, he spotted three such single transits around KIC 3542116, a faint star located 800 light years from Earth.

In a typical planetary transit, the resulting light curve resembles a sharp dip ‘U’, then an equally sharp rise, as a result of a planet first blocking a little, then a little of the light as it moves across the star. However, the light curves that Jacobs identified appeared asymmetric, with a sharp dip, followed by a more gradual rise.

This asymmetrical light curve resembled disintegrating planets, with long trails of debris that tends to block light while planet moves away from the star. In addition, there was no periodic pattern in the transits.

Rappaport whom with Jacob had collaborated in the past said, “The only thing that fits the bill, and has a small enough mass to get destroyed, is a comet.”

“These six exocomets appear to have transited very closely to their star in the past four years raises some intriguing questions, the answers to which could reveal some truths about our own solar system.”