A comet that flew past us last year from another star likely originated in a cold, isolated corner of the galaxy that had not yet formed its own solar system, astronomers said Thursday, UNN reports with reference to AP.
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Comet 3I/Atlas is only the third confirmed interstellar visitor and possibly the oldest. Scientists estimate its age to be up to 11 billion years, which is more than twice as old as the Sun.
A team led by the University of Michigan used the ALMA observatory in Chile's Atacama Desert to study the comet last autumn. The stray but harmless ice ball was discovered last summer, giving NASA and the European Space Agency (ESA) enough time to point several space telescopes at it as it sped past Mars in October and made its closest approach to Earth in December. It is now far beyond Jupiter and is finally leaving our Solar System, remaining visible only to experts.
In the study, scientists said they found an unusually high content of deuterium, or heavy hydrogen, in the comet's water. This suggests that the comet originated in a place significantly colder – even before that solar system's star formed – than our own cosmic environment, said Teresa Panek-Carreño of the University of Michigan.
While our Sun may have been surrounded by other nascent stars during its formation, she noted, this comet's home star may have been more isolated, leading to less heating and colder conditions.
The results of the study were published in the journal Nature Astronomy.
The exact origin of the comet is still unknown. Observations with the Hubble Space Telescope show that its nucleus is between 440 meters and 5.6 kilometers. It is traveling at a speed of 220,000 km/h.
"Putting all these puzzle pieces together can provide insight into what the conditions for planet formation were like in those early times," Panek-Carreño wrote in an email.
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The first known interstellar object to wander into our celestial world, Oumuamua, was discovered by a telescope in Hawaii in 2017. It was followed in 2019 by Comet 2I/Borisov, named after the Crimean amateur astronomer who first spotted it.