Icy Comets Orbiting a Star Like Our Sun Spotted for the First Time

Scientists have identified a ring of ice, dust and young comets around a star similar to our sun, shedding light on how our own solar system may have developed.

Comets and comet clouds form early in the life span of a solar system, and are primarily composed of frozen gases, rocks and dust, coalescing out of clouds of smaller particles into the cosmic bodies with trademark tails we’re familiar with.

About 160 light-years from Earth, the star — named HD 181327 and visible in the constellation Pictus — has about 130 percent the mass of our sun. Its neighborhood is also considerably younger than our own, measuring only about 23 million years in age as compared to our own solar system’s relatively wizened 4.6 billion.

ALMA image of the comet cloud around HD 181327, with colors changed for emphasis. The white contours represent the size of the Kuiper Belt in the solar system.
“Young systems such as this one are very active, with comets and asteroids slamming into each other and into planets,” said Sebastián Marino, a Cambridge Ph.D. student and the paper’s lead author, in a press release. “The system has a similar ice composition to our own, so it’s a good one to study in order to learn what our solar system looked like early in its existence.”

Understanding how carbon monoxide gas accumulated around the star will help us learn about our own solar system’s early days.. Up until now, that sort of gas cloud has only been found around a few stars, all of which have been significantly more massive than the sun. Scientists currently believe that comet impacts are what brought many elements and compounds to a still-rocky, barren Earth early in our planet’s development.

The findings, to be published in the journal Monthly Notices of the Royal Astronomical Society and presented today at a planetary formation conference in Santiago, Chile, are the result of University of Cambridge research using the Atacama Large Millimeter Array (ALMA). The space exploration tool located in the desolate Chilean desert examined the debris ring around the star, searching for signs of — and finding — gas signatures around HD 181327. The scientists also found a smaller, secondary debris ring or dust halo orbiting the star beyond the primary ring.

The researchers say the star likely has planets in orbit as well, but given the limitations of our current technology and the star system’s distance from us, they’d have to be the size of Jupiter to be detectable.

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