‘Mini galaxy’ detected in mysterious cloud at edge of Solar System

A mysterious cloud of space rocks and debris at the edge of the Solar System may have spiral arms that make it resemble a mini galaxy, a new study suggests.

The origin of the Oort cloud, a theoretical debris shell located at the gravitational edge of the Solar System, may provide more clues to how comets and our neighboring planets formed.

IT HAD PRESERVED ITS MYSTERY FOR MANY YEARS

According to Independent Turkish, the cloud is estimated to be between 2,000 and 5,000 astronomical units (AU) away; 1 AU corresponds to the distance between the Earth and the Sun.

The giant debris cloud is thought to be the source of strange comets and meteors that have passed by Earth, such as the mysterious cigar-shaped rock known as 'Oumuamua, which was spotted in October 2017.

Although previous research suggested that the Oort cloud could contain the remains of Solar System planets that formed 4 billion years ago, its exact shape and structure remained a mystery.

A new study, not yet peer-reviewed, suggests that this debris cloud could resemble a mini galaxy with spiral arms.

Using a supercomputer, the researchers modeled the structure of the Oort cloud based on the orbits of comets as well as gravitational forces within and beyond the Solar System.

In particular, they attempted to model the "galactic tide" pulling on objects at the edge of the Solar System. This corresponds to the gravitational pull that objects in the Oort cloud, such as stars and the monster black hole at the center of the galaxy, exert on objects. However, planets within the Solar System are not affected by this galactic tidal force because they are under the stronger gravitational pull of the Sun.

When the researchers simulated these forces using NASA's Pleiades supercomputer, the model showed that the Oort cloud has an internal structure similar to the spiral arms of the Milky Way Galaxy.

It was calculated that the spiral arms of the Oort cloud shown in the model are approximately 15 thousand AU long from end to end. The following expressions are used in the study:

As the galactic tide moves to separate objects from the scattered disk, it creates a spiral structure in physical space roughly 15 thousand AU long.

"The spiral is long-lived and persists in the inner part of the Oort cloud until today," the study states, adding that "direct observational detection of the Oort spiral remains difficult."