Astronomy – hungry black holes

Galaxies are a plenty of colorful mix: several hundred billion stars, most small and reddish glowing, some of the sun -like yellow glowing and a smaller proportion of glare light and bluish radiant. Many stars are also circled by a planetary system, sometimes very similar to our solar system and sometimes with planets such as the “hot Jupiters” that does not exist in the solar system. The exhausted heavenly bodies come to the active stars: white dwarf stars, often a colorful “planetary fog” testifies to their dynamic final phases, or neutron stars with supernova over remains such as the cancer fog, which are remaining from the explosive end of the watery stars. In addition, there are gas and dust clouds, sometimes brightly colored, sometimes shining from the loud dust dark like a “coal bag”- this is the name of a well-known “dark cloud”.

The accumulation is held together by gravity. From the study of the movement of objects of a galaxy you know that in addition to visible matter, a lot of “dark matter” must be mixed up – a substance that is only noticeable about gravity and that you still do not know what it consists of.

And then you can see again really black: in the center of galaxies there is a black hole, a huge collection of materials from millions to billions of sun mass. Matter, but also light that comes too close to huge gravity, is irretrievably “swallowed” – which led to the name of the “hole”.

However, the gravitational force of a black hole behaves like that of any other body. It decreases with increasing distance. More precisely: Conversely, gravitational strength is proportional to the square of the distance. A double distance means only a quarter of the gravitational force. Objects, for example stars, can therefore have a stable orbit around the black hole.

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For example, the mass of the black hole in the center of the Milky Way, called Sagittarius A* by astronomers, could be determined by the rail curves from stars to 4.3 million solar masses. The Stern S0-2 was the first whose orbit was measured exactly: it revolves Sagittarius A* once in a good 16 years, approaches him to 18 billion kilometers and has a speed of up to 27 million kilometers per hour-this corresponds to almost 2.6 percent of the speed of light!

Whether you can see a black hole or even photograph depends on the surrounding area – and its “appetite”. Matter, which is located around the black hole, can be collected from it, “acclried”. Since the matter always brings a small turning impulse, it does not simply fall into the black hole like the car key into the gully, but circles it in the form of an extensive “acceleration disc”. Due to frictional forces, the matter in the window heats up to ten million degrees Celsius and thus emits huge amounts of energy in a wide wavelength range- including radio or X-rays. The first recording of a black hole was made, for example, through pictures of the »Event Horizon Telescope«, a network of eight floor -bound radio telescopes, the hole and disc in the center of the 55 million light years away galaxy 87: 6.5 billion solar masses are severely acclaimed around 0.1 solar masses per year, whereby the matter is accelerated up to 1000 kilometers per second.

Galaxies with comparable “hungry” black holes are also among the most luminous objects in the universe, which can still be observed over huge distances. The object J0313-1806 discovered in 2021 contains a black hole of 1.6 billion solar mass and is an impressive 13.03 billion light years away from the earth-a distance record!

The black hole of the Milky Way currently shows no activity.

Which gives you questioning that astronomers and restaurateurs are interested in (in addition to their joy in stars): How long can black holes maintain their huge appetite? Or otherwise: How does the accretion start, when does it come to a standstill and can a black hole also empty its surroundings?

The black hole of the Milky Way, for example, is currently not showing any activity, no acckacy processes can be observed and energy -rich “jets”, tightly bundled matters, which are often emitted far into the environment during active phases. Only spherical structures on the level of the Milky Way (the so-called Fermi bubbles), which can be observed in the gamma ray area, indicate that the Milky Way had an active, acckreting black hole a long time ago.

Recently, scientists in the 300 million light year -old galaxy SDSS1335+0728 found the first indication of how a black hole could “wake up”. The inconspicuous galaxy suddenly showed an increased luminosity in 2019, and in 2024 it then emitted regular, intensive flashes in the X -ray area. So far it is still unclear what the unusual events could have triggered, which occur both energy -more and at larger intervals than was previously observed in other galaxies. The observations do not fully fit in with common theories, according to which a massive star came too close to the black hole, was torn torn and an accretion disc formed. In another approach, astronomers suspect that SDSS1335+0728 has a “standard configuration” made of black hole with a surrounding material disc. A surrounding star could now fly through the accretion disc that a flash is sent out every round. But completely different, previously unknown processes are possible and in further observations, the galaxy of knowledge -hungry astronomers should be examined more detailed in order to better understand the high -energy eruptions and thus the black holes.