“A visitor from a strange land…” is what we are seeing here.
When our ancestors were learning to walk upright, use their hands, and make the first simple tools, cosmic events left a mark in our galaxy that our modern society would see millions of years later.
Astronomers have tracked the path of a so-called “hypervelocity star” through time and found that it was kicked out of the huge black hole at the center of our galaxy when civilization as we know it did not exist.
This space object is called S5-HVS1 and is an “A-type main-sequence star.” Astronomers think it is the fastest thing they have ever found.
Measurements of its path show that the celestial body is moving at a speed of almost 1,755 km/s, which is about 4 million miles per hour.
Astronomers have worked out that this happened about 5 million years ago. The dramatic ejection proved what is called the “Hills mechanism.”
When a supermassive black hole shakes up a binary star, the Hill mechanism happens.
In our Milky Way Galaxy, for example, there is a supermassive black hole called Sagittarius A*. It is about 4 million times as heavy as the Sun. The Hills mechanism explains how stars are pulled apart and then left to keep traveling on their own.
What astronomers measured in 2019 was exactly that: a star being pulled into orbit around a black hole while its companion star was shot off at a very high speed into intergalactic space.
Astronomers studied kinematics and went back in time to figure out where S5-HVS1 came from. Amazingly, they found that the star could be traced back to the center of the Milky Way, where it was thrown out at a speed of 1800km/s between 5 and 4.8 million years ago. This makes S5-HVS the first clear example of the Hill Mechanism and one of the fastest stars in the galaxy.
The star was seen coming close to Earth from about 29,000 light-years away. It was moving faster than any other star in the Milky Way Galaxy by more than ten times.
Astronomers say that because of how fast it moves, one day it will leave the Milky Way galaxy and never come back.
The discovery was very important, but it also came as a surprise. Astronomers have thought for a long time that Black Holes could throw out stars at speeds that are hard to imagine. Still, they have never linked a star that moves quickly with the black hole in the middle of the galaxy.
Astronomers need to keep an eye on and measure the path of S5-HVS1 because it must have formed in the center of the galaxy. Also, it is one of a kind. The environment at the center of the Milky Way is completely different from our local galaxy. So, S5-HVS1 is a “stranger from a foreign land.”