Sagittarius A*, Star S2

Star S2's Dance With a Supermassive Black Hole and Einstein

You might have heard the recent news about a stars’ unusual orbit around a supermassive black hole at the center of our galaxy. “What does that have anything to do with Einstein?”, you might ask. Well, a lot. His General Theory of Relativity has once again been proved with the recent news from the Star S2.

In case you don’t have any time, here is a short summary of the article:

European Southern Observatory has observed that Star S2’s orbit around Sagittarius A* is in the shape of a rosette. This not only provides strong evidence that Sagittarius A* is actually a supermassive black hole, but it also proves the theory of General Relativity once again.

Einstein Smoking

Supermassive Genius of the 20th Century

This man was such a genius that the theories he came up with 100 years ago are still being proven by the scientific community. He was such a phenomenon, he is still breaking the news even to this day. 

His theory of General Relativity, published in 1915, was proved with the slight tilt in the orbit of Mercury around the Sun. “I had heart palpitations,” he said. The same principle was expected to be observed in the Star S2’s orbit around Sagittarius A* by the scientists at the European Southern Observatory. 

Sagittarius A*

Sagittarius A*, NASA, X-Ray Image

Sagittarius A* 

As we’ve explained slightly in our Galaxy Facts Article, almost all spiral and elliptical galaxies have a supermassive black hole at the center. The gravitational force towards the center is so stupendous that this is almost inevitable.

By now, it is almost certain that there is a supermassive black hole at the center of our galaxy, The Milky Way. It is called the Sagittarius A*. It is not officially declared as a supermassive black hole yet. Its official definition is “a very compact astronomical radio source”. But the evidence is so decisive that we can call it a supermassive black hole.

Star S2

Sagittarius A* has many stars orbiting around it since its gravitational pull is so huge. One of those stars is called S2.

The reason we are particularly interested in S2 is that it is the fastest one. Actually, it is now officially the fastest known object in our galaxy. Its speed reaches 2.5% of the speed of light when it is nearest to the Sagittarius A*, which is 7600 kilometers per second. The extreme speed and mass create an environment for Einsteinian physics. A tilt in the orbit occurs, creating a shape like the image below.

Rosette Orbit of Star S2, Illustration

Star S2's Beautiful Orbit

This shape is called a rosette. It comes from the French for rose, “rosé”. It is quite an amazing thing to know that a giant star is drawing roses around a black hole at the center of our galaxy. A dance of eternal darkness and light.

There is an actual video of Star S2 orbiting around Sagittarius A*, created by the European Southern Observatory. It is generated by sticking 20 years of images together. 

20-Year Time-Lapse of Star S2, European Southern Observatory, Chile

Why? General Relativity.

Let’s come back to Einstein and his theory of General Relativity. Why does this tilt happen at all? Simply because the extreme mass and speed create a distortion in space-time, slightly tilting the orbit of the Star S2.

The difference between the orbit predicted by Einsteinian Mechanics and Newtonian Mechanics is staggering. 

Elliptical Orbit

Einsteinian Mechanics

Newtonian Mechanics vs Einsteinian Mechanics, Elipse and Rossette Orbits

Dance of the Giants

Why are all these important? What does it matter if a star has an unusual orbit? It matters for two particular reasons. 

First is the fact that it provides strong evidence for the existence of a supermassive black hole at the center of our galaxy. The second one is that it proves Einstein was right about gravity and time. It proves that Einstein’s Universe was closer to reality, and our existence is based on stranger principles than we think.