The endless dance between the Milky Way

Like ballet dancers dancing around an invisible leader, dozens of stars in the Milky Way are revolving around a supermassive black hole.

The central area image of the Milky Way is taken by an infrared camera.Photo: Space.com.

Photos taken with infrared cameras show that this black hole has about 4 billion times the mass of the sun.

Astronomers have long believed that supermassive black holes are located at the center of galaxies. We cannot see black holes because their gravity is so great that they can attract light. Astronomers determine the location of black holes by tracking the movements of stars and dust around them.

For the past 16 years, astronomers from the European Southern Observatory have observed 28 stars moving around the center of the Milky Way - believed to be the hiding place of a black hole called Sagittarius A *. They used a 3.5-meter telescope at the La Silla observatory and four 8.2-meter telescopes at the Paranal observatory. Two astronomical stations are located on Chilean territory.

By tracking the movement of central stars around Sagittarius A *, researchers have speculated on some properties of black holes, such as its mass and width. They found that at least 95% of the matter affects stars that must be inside the black hole. The analytical results show that Sagittarius A * is about 27,000 light-years from Earth.

'The most striking thing in this study is that we have found empirical evidence that supersized black holes really exist , ' says Reinhard Genzel, an expert at the Institute for the Study of Physical Systems in the Surface Max Planck (Germany), said.

The latest images that infrared cameras on telescopes capture help scientists find some of the most common properties of stars around black holes. For example, the innermost star has a random orbit, while the orbits of six further stars lie on a plane (like the motion of planets around the Sun).

A star, named S2, revolves around the center of the Milky Way at such a high speed that it completes a closed loop for exactly 16 years - by the time the research is conducted.

The team hopes that further efforts will help them answer the question of the fate of the stars around Sagittarius A *. They are newly formed stars that cannot be moved too far. Scientists say they certainly do not form on current orbits, because the terrible gravitational force of a black hole does not allow that process to occur.

One of the most recent hypotheses is that the stars formed from a cloud of gas that was attracted to the black hole 6 million years ago. When approaching the black hole, most of the cloud is torn into pieces by gravity. Some pieces "escape" thanks to the chaotic movement of the air masses. The remainder forms an oval disk of dust gas that moves around the black hole.

Although moving near a black hole, the gas disk is not sucked into the hole because it is within a safe range. The changes in material density inside the gas disk make it thicken over time, eventually breaking and forming stars. These stars continue to move in oval orbits that the gas disk leaves behind. The team thinks that the existence of six stars with orbits on a plane indicates this.

The closest black hole stars ever existed in pairs. Therefore, when pairs of stars get too close to the black hole, its gravitational force causes a star to be destroyed. The remaining stars may have formed about 50 million years ago. Because they remain the same trajectory since their "companions", they move in random shapes.