For the first time, astronomers have found evidence of icy comets orbiting a nearby sun-like star, and the discovery may shed new light on how our own solar system developed, according to new research scheduled to be presented Thursday at a scientific conference in Chile.
An international team led by scientists from the University of Cambridge have detected minute levels of carbon monoxide gas around HD 181327, a star with a mass that is approximately 30% greater than the sun and which is located 160 light years away in the Painter constellation.
The carbon monoxide content in the 23-million-year-old system is consistent with that found in the comets observed in our own 4.6-billion-year-old solar system, the researchers will announce at the Resolving Planet Formation in the Era of ALMA and Extreme AO conference in Santiago. Their work will also be published in the Monthly Notices of the Royal Astronomical Society.
Lead author Sebastián Marino, a PhD student from Cambridge’s Institute of Astronomy, and his colleagues believe that their findings will ultimately help researchers determine the properties of the cometary gas clouds that typically form around sun-like star shortly after they first born.
“Young systems such as this one are very active, with comets and asteroids slamming into each other and into planets,” Marino said in a statement. “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.”
Researchers also suspect that planets may be orbiting the star
Comets, the researchers explained, are basically “dirty snowballs” of ice and rock that sometimes leave behind a trail of dust and evaporating ice. They often form early on in the star system’s life cycle, and while they are usually found in the outer reaches of our solar system, they are easier to see during the infrequent occasions when they venture into the inner regions.
When our solar system first formed, Earth is believed to have been a rocky wasteland similar to modern-day Mars, Marino and his colleagues explained. It wasn’t until comets collided with the emerging world that water and other essential compounds made their way here, and by locating the ring of dust around HD 181327, the authors believe that they may see processes very similar to those that took place shortly after the planets formed around our system’s sun.
In fact, they found a ring of dust surrounding the star that was created by collisions that involved comets, asteroids and other objects, and while they believe that there may be planets currently in orbit around the star, they are unable to directly observe them due to technological limitations.
“Assuming there are planets orbiting this star, they would likely have already formed, but the only way to see them would be through direct imaging, which at the moment can only be used for very large planets like Jupiter,” explained co-author Luca Matrà, who is also a PhD student at Cambridge’s Institute of Astronomy.
To detect the possible presence of comets, the researchers used ALMA to search for signatures of gas, and found extremely low levels of carbon monoxide gas – the lowest ever detected in a belt of comets and asteroids, according to Marino. The same collisions thought to have formed the dust ring HD 181327 are likely responsible for the release of the gases as well.
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Image credit: Amanda Smith, University of Cambridge
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