Effects not yet described: scientists discover how stars can change Earth’s climate

Every few million years, the unexpected encounter of a star with the solar system occurs . If it is a star of large mass, it can introduce gravitational disturbances which would affect the dynamic evolution of the planets, and the Earth would not escape these effects.

Recently, Two American astronomers have discovered evidence of the effect of a star encountering the solar system millions of years ago. . This would have caused variations in the Earth’s orbit and, therefore, would have brought irreparable consequences on the planet’s climate.

A work of astronomers Nathan A. Kaib and Sean Raymond, published in Astrophysical Journal Letters He demonstrated gravitational effects caused by chance encounters with stars, using simulations.

Scientists have notably analyzed the dynamic consequences of approach of the solar system of a star similar to the Sun, call HD7977 2.8 million years ago . This produced a strong destabilization of the entire solar system and led to an increase in the Earth’s orbital eccentricity. In other words, the shape of the planet’s path around the sun has been significantly changed.

Although it is still under study, Such fluctuations in Earth’s orbit are known to produce drastic changes in climate, such as the increase or decrease in global temperature.

THE paleoclimatic studies allowed us to identify climatic anomalies that could be associated with gravitational disturbances in the Earth’s orbit and this is the branch that the American scientists in this study are currently entering.

One of the episodes studied is known as Paleocene-Eocene thermal maximum and it happened 56 million years ago. At this time, the Earth’s temperature increased between 5 and 8 degrees Celsius . In fact, it was already suspected that Earth’s orbital eccentricity was remarkably high during this event.

This was discovered thanks to gravitational simulations, like the one used in this study. This technique allows you to travel to the past and deduce the evolution of the orbit of Earth and other planets over the past millions of years. THE Astrometric studies carried out by the GAIA space mission having authorized accurately quantify the movement of stars close to the Sun and minimize inaccuracies.

Before GAIA, the gravitational effects of stars passing near the Sun had not been taken into account in the evolutionary predictions of planetary orbits , due to uncertainty about stars close to the sun. However, this study confirms that it is possible to delve into this evolution over millions of years and relate it to encounters that occurred a few million years ago.

In this way, Kaib and Raymond identified the stage of the star HD 7977 towards the solar system . It is a spectral class G star currently projected into the constellation Cassiopeia, approximately 246.9 light years from Earth.

The interest of this star lies in the fact that, Having a mass similar to that of the Sun, this fleeting encounter was sufficiently powerful enough to change the predictions of simulations of Earth’s orbit around 50 million years ago. This is why it is not possible to investigate further in time.

Other limitations in the position and drift of this star which prevent us from knowing the exact details of its encounter. The current observational uncertainty makes it possible to calculate the minimum encounter distance at which HD 7977 passed from the Sun. oscillates between 4,000 and 31,000 astronomical units (AU) . In this range, HD 7977 could have had a significant impact on the eccentricity of Earth and other planets if it had moved to the lower range, a few thousand AU.

One AU is equivalent to approximately 150 million kilometers, the average Earth-Sun distance. To give us an idea, that means that the star crossed far from the central region of our solar system, less than a tenth of the distance of the most distant comets. This is the limit of the solar gravitational field at 100,000 AU, where the outermost frozen body storage area known as the Oort Cloud is located. That’s to sayone hundred thousand times the average Earth-Sun distance.

There are other possible indirect evidence for the encounter of our planetary system with other stars. Among them is the possibility that even smaller stars, like Scholz, disrupt small bodies in the Oort Cloud .

So, almost without meaning to, We have become aware of the fragility of the earth’s climate, who is also prone to wayward encounters with rogue stars.

*Josep M. Trigo Rodriguez , principal investigator of the Meteorites, Minor Bodies and Planetary Sciences group, Space Sciences Institute (ICE – CSIC). Article published in The Conversation.