The secret of the formation of spiral galaxies has been revealed

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Do you know what surprises me the most? The fact that we take the world around us for granted. Animals, plants, the laws of physics and space are perceived by many people as something so mundane and boring that they invent fairies, ghosts, monsters and witchcraft. Agree, this is amazing, because the very fact of our existence is magic.

Look at the same giraffes - how did such things with a long neck come about? And what about platypuses, echidnas, porcupines and all other animals? I think you understand what I mean. The same goes for space. Isn't the very fact of the existence of planets, stars and galaxies amazing? And isn't it great that we can study them? So, the Milky Way galaxy (in which our Sun and Earth are located) is one of the billions of galaxies in the vastness of the infinite Universe, but we managed to find out what shape it is and what shape most galaxies in the observable Universe have. In this article, you will learn something amazing about the world we live in, namely why are some galaxies spiral-shaped?

What is a galaxy?

In space, everything is controlled by the force of gravity. If not for her, then in the vastness of the infinitely expanding - and even with acceleration - the Universe would not have a single galaxy. After the Big Bang, which occurred 13.8 billion years ago, the universe continued to expand, gradually cooling down. After the end of the dark ages - starting with the condensation of neutral gas - clumps of matter gradually began to form.

The Dark Ages are the period of development of the Universe during which the first stars and relic radiation were formed.

In fact, a galaxy is a large gravitationally bound system of clusters of matter, stars, clouds of gas and dust, dark matter and planets. Moreover, all objects in the galaxy move relative to the common center of mass - a supermassive black hole located in the very heart of galaxies. Strange, isn't it? Therefore, scientists are peering into the depths of space, trying to find out as much as possible about this mysterious place.

Background radiation (or cosmic microwave background radiation) is thermal radiation that fills the universe evenly. It is believed that the relic radiation originated in the era of the early Universe, that is, shortly after the Big Bang

What shape are galaxies?

You may be surprised, but detailed studies of galaxies did not begin until the 1920s. While the stars and planets have never been deprived of human attention, the eminent scientist Edwin Hubble laid the foundation for extragalactic astronomy. He proved that many of the nebulae observed by astronomers turned out to be other galaxies composed of countless stars. Hubble has studied over a thousand galaxies and determined the distances to some of them. Moreover, it was Edwin Hubble who first identified three main types of galaxies: spiral, elliptical and irregular. It turned out that spiral galaxies in the vastness of the Universe are more common than others. Well, more than half of the galaxies are spiral, including the Milky Way, the Andromeda galaxy and the Triangle galaxy. But why?

Magnetic fields are the key to unraveling the mysteries of spiral galaxies

Scientists are still baffled by spiral galaxies and how they take shape, with graceful arms full of stars. In fact, spiral galaxies are the iconic form of most galaxies in the universe. In an effort to understand why, astronomers are closely watching spiral galaxies that are different from the Milky Way. Scientists recently observed the galaxy M77, also known as NGC 1068, using the SOFIA stratospheric observatory for infrared astronomy and presented their results in a new study, which will soon be published in The Astrophysical Journal.

A magnetic field is a special type of matter through which the interaction between moving charged particles is carried out.

According to the authors of the work in an official press release, magnetic fields play a large role in the formation of spiral galaxies such as M77. Magnetic fields are invisible, but can influence the evolution of galaxies. Today, scientists understand quite well how the force of gravity affects galactic structures, but the role of magnetic fields in these processes remains to be seen.

M77 is a spiral galaxy about 47 million light-years from Earth. The researchers concluded that M77 has an active galactic nucleus, which contains a supermassive black hole twice as massive as Sagittarius A *, the black hole at the center of the Milky Way. M77 is larger in size than the Milky Way: its radius is about 85,000 light years, and the radius of the Milky Way is about 53,000. However, there are about 300 billion stars in the M77 galaxy, while in the Milky Way there are about 250 billion up to 400. The spiral arms of M77 are filled with regions of intense star formation, called stellar flares. The magnetic field lines closely follow the spiral arms, although they cannot be seen with an ordinary telescope. Fortunately, SOFIA can do this, leading astronomers to know that the existence of magnetic fields supports a widely held theory that explains how the arms of spiral galaxies take shape. It is called "density wave theory".

Density wave theory was proposed in the 1960s to explain the spiral structure of spiral galaxies. According to this theory, the arms of spiral galaxies are not material formations, but are areas of increased density, essentially resembling traffic jams.

So, the galactic arms are the visible part of the density waves themselves, and the stars move in and out of them. Thus, the arms of spiral galaxies are not permanent structures made of stars, although they look like that. Observations with SOFIA have shown that magnetic field lines stretch along the entire arm of the M77 galaxy at a distance of 24,000 light years. According to the results obtained, the gravitational forces that helped create the spiral shape of the galaxy, as it were, compress the magnetic fields, thereby confirming the theory of density waves. Pure space madness, isn't it?

However, this study deals with only one spiral galaxy, so astronomers still have a lot of work ahead of them. It remains unknown what role the magnetic field lines can play in the structure of other galaxies, including the wrong ones, but despite a huge number of questions, we have already learned a lot about the world in which we live and this knowledge only piques curiosity.