Russian astrophysicists have proven the existence of different mechanisms for the formation of spiral galaxies. Scientists from St. Petersburg State University (SPbSU), Lomonosov Moscow State University, and the Pulkovo Astronomical Observatory (GAO RAS) have developed a new research method that has revealed the secrets of the formation of spiral arms of galaxies.
In the course of the study, experts analyzed three galaxies — M 100, NGC 3686, and NGC 2403. They applied a comprehensive approach, observing the movement of gas inside galaxies, analyzing the locations of stars of different ages, and comparing images in ultraviolet and infrared light.
The main difficulty is that there are actually few such signs. For example, the density wave scenario assumes a constant angular velocity of the pattern (“solid-state” rotation), while another scenario assumes its decrease with distance from the center (as in galaxy disks).
The researchers found that even in galaxies with clear spiral arms, such as M 100, there are not always signs of a “density wave”. These arms, characteristic of galaxies, extend from the central disk and contain many young stars and gas. The “density wave” phenomenon is similar to a traffic jam during rush hour, when stars and gas accumulate in certain places in the galactic disk. However, the presence of spiral arms does not guarantee that matter accumulates in the galaxy in the form of density waves.
At the same time, the presence of one and two types of density waves has been reliably established for the first time in the galaxies NGC 3686 and NGC 2403.
The discovery is important for understanding the evolution of galaxies and the formation of their structure. The results of the study will help scientists better understand the processes occurring in the Universe and refine existing theories of the formation of cosmic objects.
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