An artist's illustration of the interstellar asteroid 'Oumuamua.
Credit: M. Kornmesser / European Southern Observatory
The first known interstellar visitor to the solar system, 'Oumuamua, highlights how life could also spread across the stars, and perhaps even across the galaxy, two new studies find.
In 2017, astronomers detected a cigar-shaped asteroid named 'Oumuamua, or A / 2017 U1, a chaotically tumbling 1,300-foot-long (400 meters) object whose trajectory suggests it may come from another star, or perhaps two. Researchers have learned that 'Oumuamua is unlike anything seen in the solar system,
Previous research has estimated that there are about a million billion interstellar objects comparable in size to 'Oumuamua per 35 cubic light-years, much higher than some prior estimates. This led scientists to explore the implications of such astronomical numbers of 'Oumuamua-like bodies might have for the prospect of lithopanspermia – the idea that life might have spread throughout space by hitchhiking on rocks. [‘Oumuamua: The Solar System’s First Interstellar Visitor in Photos]
"Interstellar objects could potentially plant life from another solar system," Avi Loeb, an astrophysicist at Harvard University and senior author, Space.com.
The group calculated the rate at which the sun and Jupiter could gravitationally capture interstellar objects such as' Oumuamua and found the largest body they could trap a few dozen miles wide. They performed similar calculations for the Alpha Centauri and B binary systems and found it could capture Earth-size interstellar objects.
The researchers also estimated that an interstellar object about 0.6 miles (1 kilometer) wide might typically strike Earth every 10 million to 100 million years. Such collisions might have helped deliver organic compounds or even microbes to Earth, they said.
"Life can spread across vast distances," study lead author Manasvi Lingam, an applied mathematician at Harvard University, told Space.com. Lingam and Loeb describe their findings from the first study online Oct. 12 in the Astronomical Journal.
The scientists then explored how many rocky asteroids or icy comets ejected from one planetary system can get trapped by another one across the entire Milky Way. They have an interstellar object, and the number of stars in the Milky Way, the distances between the stars, and the amount of time it takes for an interstellar object. amount of time may be possible to stay alive.
"Bacteria can survive for many millions of years," Idan Ginsburg, an astrophysicist at Harvard University and lead author of the second study, told Space.com. "If the rocky body was large enough, bacteria would be shielded from the most radiation, and when it entered the atmosphere, the object would get scorched, inside microbes could survive."
The researchers estimated that "if life can survive for a million years, there can be over a million people." Oumuamua-size objects are captured by another system and can transfer life between stars, "Loeb said.
All in all, "life could spread throughout the entire galaxy through panspermia," Ginsburg said. In principle, galactic panspermia might not only bring life to life planets, but spread one form of life to a planet with a different form of life, he added.
In addition, "in principle, life could have been transferred between galaxies, since some stars escape from the Milky Way," Loeb said. "These stars could potentially transfer life throughout the universe."
Ginsburg, Lingam and Loeb. 10 in a study submitted to the Astrophysical Journal Letters.