A rogue star grazed our solar system billions of years ago

Scientists say a close shave with a rogue star making a career in our solar system billions of years ago could provide an explanation for the warped orbits of several mysterious objects beyond Neptune.

The stellar flyby has scattered thousands of small icy worlds of our star system into strange positions and orbits, the researchers suggest in a new article.

The new theory could help explain some unusual features of the solar system, including the unusual trajectories of dwarf planets like Sedna, which causes the sun to ring once every 11,400 Earth years.

It also provides an explanation of the mysterious “Planet X”, which some claim resides in our system, after the dwarf planet Pluto.

The object is thought to be ten times the size of Earth – far too large for anything to have formed this far from the sun – but the new theory suggests that the planet is in fact the same size as Earth.

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A new theory about how the solar system was formed could help explain some of its unusual features, including the bizarre positions and orbits of dwarf planets. It can also explain the existence of a mysterious planet X (artist’s impression) on the outskirts of our system.

Objects in the outer solar system, including Sedna, are described as transneptunian, with many of them having unexplained trajectories and sizes.

About 20 of these objects have orbits that are tilted and stretched relative to the rest of the solar system, which some scientists say have been distorted by a passing star.

Lead author of the study, Professor Susanne Pfalzner, said New Scientist: “You might well have some sort of hybrid scenario, where the movement of the planets is responsible for things that we find in the inner solar system, like the low mass of Mars, and a flyby. [is responsible] for the properties of the outer solar system. ‘

His team at the Max Planck Institute for Radio Astronomy in Bonn, Germany, tested this theory using recent data on the behavior of young stars.

They connected this data to thousands of star-fly simulations to see if a rogue star could have helped shape the early solar system billions of years ago.

Over a period of about a billion years, the chances of a star grazing our system to disrupt some of its planets were about one in four, the models showed.

A rogue star may have grazed our solar system billions of years ago - and that may explain the distorted orbits of several mysterious objects.  The stellar flyby dispersed thousands of small icy worlds of our star system, like the dwarf planet Sedna (artist's impression)

A rogue star may have grazed our solar system billions of years ago – and that may explain the distorted orbits of several mysterious objects. The stellar flyby dispersed thousands of small icy worlds of our star system, like the dwarf planet Sedna (artist’s impression)

WHAT IS SEDNA?

Sedna is a minor planet discovered in 2003.

It orbits the Earth’s sun at a distance of eight billion kilometers but appears to be separate from the rest of the solar system.

Detached objects like Sedna get their name from the fact that they perform gigantic circular orbits which do not bring them closer to large planets like Jupiter or Neptune.

How they got to the outer solar system on their own is an ongoing mystery.

One theory for its unusual dynamics is that a ninth planet still invisible beyond Neptune may have disrupted its orbit and other detached objects.

Scientists now say bumper car-like interactions at the edge of the solar system explain the dynamics of “loose bodies” such as Sedna.

Researchers believe that smaller objects such as asteroids could crash into objects called Sedna, dramatically changing orbit.

As space debris interacts in the outer solar system, the orbit of these objects tightens and widens over time, the researchers say.

The researchers said this means that such an event is likely to have occurred at some point in the history of our solar system.

The team modeled the early solar system after readings from young stars, simulating a disk of particles that decrease in density as it moves away from the sun.

They found that a star of similar mass to our sun creates something similar to the solar system if it exceeds 80 to 100 AU – or 80 to 100 times the distance between Earth and the sun – during the early formation of our system.

He achieved this by pushing thousands of small, frozen worlds into interstellar space beyond Neptune, leaving behind only a few transneptunian objects.

Objects in the Outer Solar System, including Sedna, are described as trans-Neptunian, and many - including Sedna (bottom left) and an as yet unidentified new planet (right) - have unexplained sizes and trajectories

Objects in the Outer Solar System, including Sedna, are described as trans-Neptunian, and many – including Sedna (bottom left) and an as yet unidentified new planet (right) – have unexplained sizes and trajectories

The flyby pushed so much material out that it created a sharp drop in mass beyond 30 AU, much like that seen in our star system.

The results of the model could finally solve the mystery surrounding the orbits and strange positions of many transneptunian objects.

Scientists who disagree with the stellar flyby theory suggest that the objects were actually created where Neptune and Uranus are now, and then migrated outward when the former moved away from Earth. .

A star crossing may also explain the odd size of Planet X – a yet unidentified world that scientists have only deduced from its gravitational pull on other objects.

Planet X, also known as planet nine, is said to be ten times the size of Earth – far too large for anything to have formed this far from the sun.

In Max Plack models, the planet was actually the same size as Earth, but still had the same gravitational impacts observed by astronomers.

PLANET NINE: OBJECT ORBITS BEYOND NEPTUNE SUGGEST THERE’S SOMETHING BIG

Astronomers believe that the orbits of a number of bodies in remote regions of the solar system have been disrupted by the pull of an as yet unidentified planet.

First proposed by a CalTech group in the United States, this alien world was theorized to explain the distorted paths observed in distant frozen bodies.

In order to accommodate the data they have, this alien world – commonly known as Planet Nine – would need to be about four times the size of Earth and ten times its mass.

Researchers say that a body of this size and mass would explain the clustered paths of a number of icy minor planets beyond Neptune.

First proposed by a CalTech group in the United States, this alien world was theorized to explain the distorted paths observed in distant frozen bodies.

First proposed by a CalTech group in the United States, this alien world was theorized to explain the distorted paths observed in distant frozen bodies.

Its enormous orbit would mean that it would take between 10,000 and 20,000 years to make a single revolution of the sun.

The theoretical nine planet is based on the gravitational pull it exerts on these bodies, with astronomers confident that it will be found in the years to come.

Those hoping for theoretical Earth-sized planets proposed by astrologers or science fiction writers – which are “hiding behind the sun” and tied to doomsday scenarios – may need to keep looking.


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Arline J. Mercier