2024-02-14 16:59:40
Stars passing close to our Solar System have altered the long-term orbital evolution of planets, including Earth, and by extension have modified our climate.
“Perturbations (a minor deviation in the course of a celestial body, caused by the gravitational pull of a neighboring body) caused by passing stars alter the long-term orbital evolution of the Sun’s planets, including Earth,” he explains. Nathan A. Kaib, senior scientist at PSI (Planetary Science Institute), as a conclusion to a study published in Astrophysical Journal Letters.
“One of the reasons this is important is because the geological record shows that changes in Earth’s orbital eccentricity accompany fluctuations in Earth’s climate. If we want to better look for the causes of ancient climate anomalies, “It’s important to get a sense of what Earth’s orbit was like during those episodes,” Kaib said in a statement.
“An example of such an episode is the Paleocene-Eocene Thermal Maximum 56 million years ago, where the Earth’s temperature increased by 5 to 8 degrees Celsius. It has already been proposed that the Earth’s orbital eccentricity was remarkably high during this event, but our results show that passing stars make detailed predictions of Earth’s past orbital evolution at this time very uncertain, and a broader spectrum of orbital behavior is possible than previously thought.”
Simulations (run backwards) are used to predict the past orbital evolution of the Earth and the other planets of the Sun. Analogous to weather forecasting, this technique becomes less accurate as it is extended to longer periods due to the exponential growth of uncertainties. Previously, the effects of stars passing near the Sun were not considered in these “backward forecasts.”
As the Sun and other stars orbit the center of the Milky Way, they can inevitably pass close to each other, sometimes within tens of thousands of au, with 1 AU being the distance between the Earth and the Sun. These events are called stellar encounters. For example, a star passes 50,000 AU from the Sun every 1 million years on average, and a star passes 10,000 AU from the Sun every 20 million years on average. The simulations in this study include these types of events, while most previous similar simulations do not.
One of the main reasons why Earth’s orbital eccentricity fluctuates over time is because it receives regular perturbations from the giant planets in our Solar System (Jupiter, Saturn, Uranus and Neptune). When stars pass close to our Solar System, they disturb the orbits of the giant planet, which consequently alters the orbital path of the Earth. Thus, the giant planets serve as a link between the Earth and the passing stars.
Kaib said that when simulations include stellar passages, we find that orbital uncertainties grow even faster, and the time horizon beyond which predictions from these backward simulations become unreliable is more recent than previously thought. This means two things: There are past times in Earth’s history when our confidence in what the Earth’s orbit was like (for example, its eccentricity or degree of circularity) has been too high, and the orbital state is not known. real, and the effects of passing stars make possible regimes of orbital evolution (prolonged periods of particularly high or low eccentricity) that were not predicted by previous models.
“Taking these results into account, we have also identified a known recent stellar passage, the Sun-like star HD 7977, which occurred 2.8 million years ago, which is potentially powerful enough to alter the simulations’ predictions of how was the Earth’s orbit beyond regarding 50 million years ago,” Kaib said.
However, the current observational uncertainty regarding the closest encounter distance of HD 7977 is large, ranging between 4,000 and 31,000 Astronomical Units. “For larger rendezvous distances, HD 7977 would not have a significant impact on Earth’s rendezvous distance. However, near the smaller end of the range, it would likely alter our predictions of Earth’s past orbit,” Kaib said.
1707932487
#Stars #alter #Earths #climate #pass #Solar #System
