Astrophysics International centre for radio astronomy research (ICRAR) and the University of Western Australia came up with some interesting findings in recent studies: regardless of the size and weight, all disk galaxies in the Universe are United by one common part – they all make one complete revolution around its axis in about 1 billion years.
Among disk galaxies are lenticular and spiral like our milky Way or the Andromeda Galaxy nearby. In this sense, disk galaxies can be compared with the cosmic clock, the researchers note in an article published in the journal the Monthly Notices of the Royal Astronomical Society.
“Of course, we are not talking about the level of accuracy of a Swiss watch, but they all share one thing: no matter what galaxy we take a very large or tiny, being on the edge of this galaxy, you make one revolution around its axis in about one billion years,” explains study leader Dr. Gerhardt Meurer from the University of Western Australia.
This is the conclusion researchers came to after measuring the radial speed of neutral hydrogen 130 galaxies, differing in size, in some cases, 30 times. Astrophysicists say that the same velocity is typical for dense and large galactic objects and for clusters of the same size, but much lower density.
Astronomers also note that with the help of simple mathematical transformations it can be shown that all galaxies of the same size have roughly the same mean internal density.
“The discovery of such patterns in galaxies helps to better understand the mechanics of the rotation — you will not find a rapidly rotating dense the galaxy, the other galaxy of the same size but lesser density, rotates slowly,” says Professor Meier.
In addition, the researchers draw attention to one interesting fact that they discovered in the survey. At the outer edge of the galactic disk are not only a dense cluster of young stars and interstellar gas, but also a large number of much older stars mixed with young and interstellar gas. From the galactic disk is fairly clear boundary. This knowledge will help astronomers more accurately determine the boundaries of galaxies, which in turn will save resources when observations of boundary regions of galaxies.
The researchers make the reservation that a confirmation of the universality of their discoveries with regards to the velocities of galaxies are to be measured on a broader set of disk galaxies, to completely eliminate any bias.