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A new study reveals that the first meteor to have touched the Earth since interstellar space – and the second interstellar visitor known as a whole – has just been discovered.
Interstellar meteors may be common and could potentially help life to travel from star to star, added researchers.
The first known visitor to interstellar space, a cigar-shaped object named & # 39; Oumuamua, was detected in 2017. Scientists have deduced the origins of the object of a length of 400 meters (400 meters) of its speed and its trajectory, suggesting that it could come from from another star, or even two.
Related: & # 39; Oumuamua: our first known interstellar visitor explained in pictures
Avi Loeb, Harvard University Chair in Astronomy, noted that smaller interstellar visitors would be much more common. Some of them sometimes bumping into the Earth quite often to be remarkable.
At present, Loeb and his lead author, Amir Siraj, an undergraduate at Harvard University, have suggested that they would have detected such an interstellar meteor, the second known interstellar visitor of the solar system.
The scientists analyzed the Center for the study of objects close to the Earth& # 39; catalog of meteors detected by US government sensors. They focused on the fastest meteors because a high speed suggests that a meteor is not potentially gravitationally bound to the sun and can therefore come from outside the solar system.
The researchers identified a meteor approximately 0.9 meters wide detected on January 8, 2014 at an altitude of 18.7 km above a point near Manus Island. in Papua New Guinea, in the South Pacific. The scientists explained that its high speed (216 000 km / h) and its trajectory suggested that it came from outside the solar system.
"We can use the atmosphere of the earth as a detector of these meteors, which are too small to be seen otherwise, "Loeb told Space.com.
The speed of the meteor suggested that he receives a gravitational boost during his trip, perhaps from the deep interior of a planetary system, or from a star in the thick disk. of the Milky Way.
"You can imagine that if these meteors were ejected from the habitable area of a star, they could help transfer life from one planetary system to another," Loeb said.
Scientists have analyzed about 30 years of data. In addition to the discovered interstellar meteor, they also noted two other meteors that were traveling at about the same speeds. However, Siraj and Loeb noted that the orbit of one of these meteors suggested that it was gravitationally related to the sun, while it was not sure whether the other was interstellar or not.
Assuming the Earth sees three meteors The researchers estimated that there were about a million such objects per cubic astronomical unit in our galaxy with potential interstellar origins every 30 years or so. (An astronomical unit, or AU, is the average distance between the Earth and the sun – about 150 million km).
This suggests that each nearby star could gravitationally extract about 60 billion billion such rocks from its system, which is about 0.2 to 20 times the mass of the Earth. Ten billion billion, "is about the number of stars in the observable universe," Loeb said.
Siraj and Loeb noted that analyzing gaseous debris from interstellar meteors as they burn in the Earth's atmosphere could illuminate the composition of interstellar objects, on which much remains unclear.
In the future, astronomers may want to set up an alert system that will automatically trigger telescopes on high-speed moving meteors to analyze their gaseous debris, Loeb said. "We can deduce interstellar meteoric compositions," he said.
The scientists detailed their findings in an article that was submitted to The Astrophysical Journal Letters. You can read a pre-print for free at the address arXiv.org.
Follow Charles Q. Choi on Twitter @cqchoi. Follow us on twitter @Spacedotcom or Facebook.
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