A team of researchers from the University of Hawaii and Yale University has published an article on the effects of close flybys of stars. They tried to answer the following question: could such an event have led to a sudden change in the Earth’s climate 56 million years ago?
Close star flybys and their consequences
The solar system is located in a relatively sparsely populated region of the Milky Way, so close flybys of stars occur much less frequently there than in other parts of the galaxy. But they still happen.
The most famous of them was probably the flight of the Scholz’s star. About 70,000 years ago, it passed through the Oort Cloud, a “repository” of long-period comets and icy planetesimals located on the outskirts of our solar system. Perhaps Scholz’s star influenced some of them, but if so, we won’t know about it for another couple of million years. That is exactly how long it takes comets from the Oort Cloud to reach the inner part of the solar system.
An increased risk of comets falling is far from the only possible effect of a star passing close by. It can also affect the Earth’s orbit, which in turn will lead to changes in its climate.
Did a wandering star cause global warming on Earth?
It has recently been suggested that some of the dramatic changes in Earth’s climate were actually caused by close flybys of stars. Among the candidates is the so-called Paleocene-Eocene Thermal Maximum (PETM), which occurred 56 million years ago. It led to a global temperature increase of 5–8 °C and a massive influx of carbon into the atmosphere and oceans. The temperature increase took between 10,000 and 20,000 years and lasted for about 100,000 to 200,000 years.
The PETM had a huge impact on the biosphere. Many marine organisms became extinct, tropical and subtropical regions spread toward the poles, and primates and other mammals appeared.
In an article published last year, planetary scientists Nathan Kaib and Sean Raymond concluded that the close flyby of the star could indeed have affected Earth and led to dramatic climate changes. However, researchers from the University of Hawaii and Yale University disagree with their colleagues’ conclusions. To determine whether star flights could be the cause of the PETM and other climate changes, they used a more sophisticated model of the solar system and random stellar parameters in 400 simulations. The total number of star flights was 1,800.
Scientists have been unable to detect any influence of stars on paleoclimate reconstructions over the past 56 million years. One reason for this difference in results is the completeness of the models used to simulate the flights. For example, some of them did not include the Moon, which has a stabilizing effect on Earth. With its inclusion in the simulation, it became clear that even extremely close flybys did not seem to have any noticeable effect on our planet.
According to Sciencealert
