Monday, Jul 23, 2018

Alien star grazed our solar system 70,000 years ago

Alien star grazed our solar system 70,000 years ago
23 Mar
2018

Around 70,000 years ago our ancient ancestors may have witnessed an incredible sight in the night sky, new research suggests.

A small star, known as Scholz's star, approached our solar system, sending comets and asteroids from the outer reaches of the solar system towards its centre.

At a time when humans were beginning to leave Africa and Neanderthals were still living on our planet, the star came within less than a light year of the sun.

It is likely that they saw this star, millennia ago, as a faint reddish light glowing overhead in the area around the Big Dipper - also known as The Plough.

Experts believe that the trajectories of a number of distant space rocks in our solar system still bear the mark of this close encounter to this day.

Astronomers from the Complutense University of Madrid and the University of Cambridge analysed nearly 340 objects with hyperbolic orbits found in the solar system.

They are marked by a very open V-shaped orbit around the sun, not the typical elliptical orbit we normally think of.

Researchers found that the paths of some of these objects, known as Oort cloud comets, were influenced by the passage of Scholz's star.

The Oort Cloud contains trillions of comets left over from the birth of the universe and is thought to represent the outer limit's of the sun's gravitational pull.

The gravity of Scholz's star is believed to have dragged some of these closer toward the sun, where they became trapped in these unusual orbits.

The discovery of Scholz's star was made public in 2015 by a team of astronomers led by Professor Eric Mamajek of the University of Rochester.

Scholz´s star, named after the astronomer who discovered it, is actually a binary system.

It is formed by a small red dwarf, with about nine per cent of the mass of the Sun, around which orbits a much less bright and smaller brown dwarf, a failed star that was too small to spark into life.

Nowadays it is almost 20 light-years away, but 70,000 years ago it entered the Oort cloud, located beyond Neptune at the confines of the solar system.

Simulations conducted as part of the new study also suggest that Scholz's star approached even closer than the 0.6 to 0.8 light-years suggested in the 2015 paper.

'Using numerical simulations we have calculated the radiants or positions in the sky from which all these hyperbolic objects seem to come,' co-author Carlos de la Fuente Marcos said in a written statement.

'In principle, one would expect those positions to be evenly distributed in the sky, particularly if these objects come from the Oort cloud.

'However, what we find is very different: a statistically significant accumulation of radiants.

'The pronounced over-density appears projected in the direction of the constellation of Gemini, which fits the close encounter with Scholz´s star.'

The close fly-by of this star 70,000 years ago did not disturb all the hyperbolic objects of the solar system, only those that were closest to it at that time.

'For example, the radiant of the famous interstellar asteroid Oumuamua is in the constellation of Lyra (the Harp), very far from Gemini, therefore it is not part of the detected over-density, 'Dr De la Fuente Marcos added.

He is confident that new studies and observations will confirm the idea that a star passed close to us in a relatively recent period.

The full findings of the study were published in the journal Monthly Notices of the Royal Astronomical Society: Letters.

Scholz's star was first discovered in 2014 by Ralf-Dieter Scholz but unlike other stars around it, it appeared to have an unusual motion in the sky.

A team of scientists from the US, Europe, Chile and South Africa used observations of its motion to trace back its trajectory.

They found that the star is moving away from the Earth at great speed and came alarmingly close 70,000 years ago.

They calculated that the star, which also has the catchy name WISE J072003.20-084651.2, passed five trillion miles away from our sun. Proxima Centauri, our closest neighbour, is 4.2 light years away.

At its closest, Scholz's star would have been moving across the sky at an 70 arcseconds per year. At this speed it would have moved the distance of the Moon in the sky in 26 years.

WHAT IS SCHOLZ´S STAR?
Scholz´s star, named after the astronomer who discovered it, is actually a binary system.

It is formed by a small red dwarf, with about nine per cent of the mass of the Sun, around which a much less bright and smaller brown dwarf orbits.

The star, also known as WISE J072003.20-084651.2, was first discovered in 2014 by Ralf-Dieter Scholz.

Unlike other stars around it, it appeared to have an unusual motion in the sky.

In 2015, experts from the University of Rochester calculated that the star passed five trillion miles away from our sun, or 0.8 light years, around 70,000 years ago.

Proxima Centauri, our closest neighbour, is 4.2 light years away.

In 2018, a new study found that this stellar encounter left a lasting impact on the asteroid and comets of the Oort Cloud.

This sent them from the outer reaches of the solar system towards its centre, as evidenced by their unusual orbital trajectories around the sun.

Astronomers from the Complutense University of Madrid and the University of Cambridge analysed nearly 340 objects with hyperbolic orbits found in the solar system.

This are marked by a very open V-shaped orbit around the sun, not the typical elliptical orbit we normally think of.

Researchers found that the path of some of these objects, known as Oort cloud comets, was influenced by the passage of Scholz's star.

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