In the process of galaxy evolution, galaxies will form different shapes for various reasons, and the different forms of these galaxies are closely related to their evolution process.
Characteristics and genesis of spiral galaxies
Spiral galaxies are one of the most common types of galaxies in the universe, and the whole of the galaxy shows a very obvious spiral structure, which is composed of a disk-like structure and a convex core at the center of the galaxy.
Around the core of the galaxy, there will be many spiral arms, and in these spiral arms, there are a large number of star systems, gas, cosmic dust and other materials, forming a spiral structure around the core.
Spiral galaxies are also divided into two types in their shape, the most common spiral galaxies and the rod-shaped spiral galaxies, and the Milky Way belongs to spiral galaxies. The core of the galaxy has no obvious rod-like structure.
The core, which has an obvious rod-like structure, usually shows a very obvious shape, and the spiral arm also extends outward around the rod-like structure.
According to the theory that the formation of spiral galaxies is mainly due to the gravitational pull of the core and the gravitational pull of dark matter, which causes the surrounding gas and dust and other materials to form a rotating gas cloud, and finally evolves to form this galaxy structure.
These materials gather together under the action of gravity, and gradually form stars and other celestial bodies while rotating around the core, and these materials form the cantilever structure of galaxies under the action of gravity, and finally form the flat galaxy structure of spiral galaxies.
Characteristics and genesis of elliptical galaxies
In the evolution of galaxies, galaxies and galaxies also interact with each other, and when galaxies and galaxies gradually get closer to each other due to the effect of gravity, galaxies will merge, and the galaxies formed after this merger are likely to form elliptical galaxies.
The shape of an elliptical galaxy is characterized by an elliptical appearance, with the center of the galaxy being very bright, and the outer part of the galaxy gradually darkening at the edges.
In elliptical galaxies, the movement of stars is mostly irregular, which is completely different from the regular rotation of stars in spiral galaxies.
In elliptical galaxies, because of the irregular movement of celestial bodies, the interstellar matter in the galaxy has become very scarce, which also makes there are very few young stars in the galaxy, most of which are mainly old stars.
Because of the age of the stars, they also have high temperatures and brightness, which also causes the entire elliptical galaxy to have a very bright light, which gives it a yellow or red appearance, completely distinguishing it from the light blue spiral galaxies.
The mass of all spiral galaxies is also very large, and the mass of dwarf elliptical galaxies may be similar to that of globular clusters.
For some giant elliptical galaxies, which have a large mass, look for giant elliptical galaxies, which may contain the largest star system in the universe.
Rather, for the origin of elliptical galaxies, the most said is that two galaxies or multiple galaxies were formed after the merger, which was originally a spiral galaxy, but after the merger, they combined with each other and had a huge impact on their internal affairs, and at the same time, an elliptical galaxy was formed.
There is also a theory that in the early days of the universe after the Big Bang, due to the intense scene of the formation of galaxies in the universe at the beginning, in the process of evolution, due to the formation of very dense stars, the region eventually collapsed, and finally formed elliptical galaxies.
Characteristics and causes of irregular galaxies
Compared with spiral galaxies and elliptical galaxies, the biggest feature of irregular galaxies is that they do not have obvious cores and cantilevers, and even irregular galaxies do not have disk-like structures.
Such galaxies are usually very chaotic in appearance, without any regular shape, and for this type of galaxy, they are collectively called irregular galaxies.
Irregular galaxies are also usually mostly blue, but some of them are red, but because of their irregular shape, they also lack specific structures such as recognizable cores.
There are also different theories about the cause of the formation of irregular galaxies, and some scientists have proposed that irregular galaxies may have evolved from spiral galaxies or elliptical galaxies. Due to the influence of gravity and other reasons, the shape eventually changed.
In addition, it is also possible that irregular galaxies are composed of some relatively small clusters of galaxies, which are also gradually brought together through the interaction of gravity, and finally form this irregular galaxy shape.
However, in the early stage of the evolution of galaxies, it is also possible that the gas cloud will collapse after a lack of certain conditions, and then the evolution of the galaxy will not stop, and eventually this irregular galaxy will be formed.
Characteristics of lensed galaxies
In addition to these common galaxy forms, there are other types of galaxies such as lensed galaxies, and according to their different external forms, the evolution of galaxies has a variety of different evolutionary results.
Between spiral galaxies and elliptical galaxies, there is such a lens galaxy shape similar to a convex lens, which does not have a flat structure like spiral galaxies, and is not as variable as spiral galaxies.
The center of the lens galaxy also has a core, and some are even the core of a rod-like structure, and there are clusters of stars on the periphery of the core. But the lens galaxy does not have a very well-defined spiral arm.
The diversity of these forms reflects the complexity and diversity of the distribution of matter in the universe, and different types of galaxies also have their own unique morphological and structural characteristics, which are inseparable from their evolutionary history.