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Exocomets could be as common as exoplanets, astronomers say

January 08, 2013|By Amina Khan
  • Comets fall toward the young star Beta Pictoris in this artist's depiction, as seen from the outer edge of its disk.
Comets fall toward the young star Beta Pictoris in this artist's depiction,… (Lynette Cook / NASA )

A team of astronomers has discovered half a dozen exocomets, which may be as common as exoplanets orbiting other stars, researchers said Tuesday.

The research, presented Monday at the American Astronomical Society meeting in Long Beach, could provide tantalizing clues about the growth and evolution of alien planetary systems. 

“We’ve found essentially the leftover building blocks of planetary systems,” said UC Berkeley astronomer Barry Welsh, who presented the research.

Comets around other stars may seem hard to find, given that exoplanets are already a challenge and comets are much smaller -- typically 3 to 13 miles wide. But using a telescope at the McDonald Observatory in Texas, Welsh’s team looked for hints of comets that had evaporated as they fell toward their stars, leaving a recognizable mark on their home stars' light signatures.

Searching the skies for Earth-like planets outside our solar system, or exoplanets, scientists have found many fully formed, multi-planet systems around other stars – what might be considered adult systems. They’ve also found what look like infant systems, stars with a primordial disk of gas and dust surrounding them, looking much like our solar system must have in its early stages before the debris coalesced to form the planets.

In our own solar system, icy comets represent some of the leftover debris that didn’t make it into a planet in the solar system’s formation. As such, they’re a developmental link between the infant solar system’s proto-ring of debris and the planet, moon and asteroid belt-filled system we see today.

“Everybody switched to exoplanets because that’s where the money is and that’s where the sex is,” Welsh said. But the six exocomets reported at the meeting provide an unmined source of information about these far-off star systems. 

Scientists think comets could have brought water, one of the building blocks for life, to Earth as well to the other terrestrial planets, Welsh said. Perhaps they did the same for exoplanets as well.

Follow me on Twitter @aminawrite.

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