Galaxies are expanding systems of dust, gas, dark matter, and a million to a trillion stars held together by gravity. You can learn more about galaxies in this article. Characteristics of Galaxies.
What are galaxies?
If you look up into the night sky with a telescope and see beyond what is visible to the naked eye, you will see many Stars that in reality those points of light are galaxies, collections of millions to trillions of stars, galaxies are composed of stars, dust and dark matter, all held together by gravity. To better understand how these cosmic structures form, you can read about the galaxy and star formation.
Astronomers aren't sure exactly how galaxies formed. After the Big Bang, space was composed almost entirely of hydrogen and helium. Some astronomers think gravity pulled dust and gas together to form individual stars, and those stars coalesced into collections that eventually became galaxies.
Features
Galaxies mostly have black holes in their centers that manage to originate a formidable amount of energy, in this way astronomers can see long distances, in some cases, the central black hole of a galaxy is considerably large or active, even in very large galaxies. little.
Composition:
Here are the three ingredients that make up galaxies:
The stars: To the naked eye, the Milky Way appears as a whitish cloud, the stars that make up our galaxy have varying masses and temperatures.
Natural gas: The gas contained in galaxies (essentially hydrogen) is found in various states, there are large cold clouds of molecular hydrogen that represent approximately half of the total mass of gas in the region included in the orbit of the Sun.
Dust: galaxies also contain dust that the stars have formed during their useful life and that have been expelled into the interstellar medium, these dust particles have the property of absorbing the light emitted by the stars, just as dust suspended in the air absorbs the sunlight.
Color
Both the arms and the disk of a spiral system are blue, while its central areas are red like an elliptical galaxy.
The hottest and youngest stars are blue, the oldest and coolest are red, so the center of a spiral is made up of old stars, with young stars in the arms recently formed from gas and dust.
superstructures
Above the large-scale spiral structure of the galaxy is a chaotic distribution of smaller entities within the galaxy itself. This complex morphology is also recognized in other spiral and irregular galaxies and clearly results from strong localized depositions of energy in the interstellar medium.
Categories of Galaxies
Although there are different types, each galaxy contains the same elements, but these are organized differently for each type. Just as a human being is created with the same uniquely configured proteins, galaxies are also created with gases, dust, stars, and other elements. For more information, you can consult the types of galaxies that exist.
Galaxies Spirals
A spiral galaxy has a disc, a bulge and a halo, the center of the galaxy is like a nucleus, containing a sphere-shaped bulge that houses old stars and is devoid of dust and gas, the circular shape of the galaxy makes up the disk. The arms of the galaxy originate from the disk and are where new stars will form in a galaxy.
The sun in our galaxy is located in an arm, and its stars form in this part of the galaxy and has the greatest amount of gas. This area thrives on blue stars. The halo is a spherical collection of stars and ancient clusters known as globular clusters that are found on the outer edge of the galaxy. You can also visit the article on galaxies near the Milky Way.
Elliptical Galaxies
Elliptical galaxies can be recognized by their elongated spherical shape and their lack of a nucleus or bulge in the center. Although there is no nucleus, the galaxy is still brightest in the center and becomes less radiant towards the outer edges of the galaxy.
Stars, gases and other materials are spread throughout the elliptical galaxy, an elliptical galaxy can be nearly round or long and cigar-shaped.
Much of the mass in an elliptical galaxy is thought to be due to the presence of a central black hole. These galaxies have very little activity and contain mostly old, low-mass stars, because there is no gas and dust needed to form new stars.
Irregular Galaxies
Irregular galaxies are composed of gases, dust, stars, formation Nebula, neutron stars, black holes and other elements common to all galaxies.
Irregular galaxies are so named because they have no defined shape, but like all galaxies, they are constantly moving, moving outward and away from the center of our universe. Irregular galaxies are divided into two classifications: IMR and IO.
IM galaxies occur most frequently among irregular galaxies and may show a trace of the arms of spiral galaxies, IO galaxies are completely random and can be called chaotic in nature. Approximately 20% of our galaxies are classified as irregular. Additionally, you can learn more about the dwarf galaxies.
Lenticular Galaxies
They clearly exhibit a bulge and disk similar to spiral galaxies, but show no signs of spiral arms or significant amounts of interstellar material, the origins of the S0 galaxies are still unknown, but one idea is that they were originally spiral galaxies that lost or depleted its interstellar material through interactions with another galaxy.
Active Galaxies
An active galaxy emits thousands of times more energy than a normal galaxy, most of which is released not in visible light but in other wavelengths, from radio waves to gamma rays. In addition, long jets of gas can be released from the galaxy at nearly the speed of light. This activity is driven by a supermassive black hole at the galaxy's core. For more information, see this article on active galaxies and the James Webb Telescope.
galaxy formation
There are many theories about the formation of galaxies here we name two of them:
Collapse formation theory
Galaxies are believed to have started from large irregular clouds of hydrogen and helium, this gas was created in the first minutes of the universe, certain sections of the Clouds they were probably a little denser than others, because of this higher density, gravity caused their collapse, this process of collapse, gives us stable galaxies.
Fragmentation formation theory
The further evolution of galaxies containing such thin gas layers or sheets that they may involve the fragmentation of these sheets into filaments or clumps, which eventually collapse to form stars.
The movements of the galaxies
All galaxies have their own rotational motion around their core and translational motion along with the galaxies in the cluster they are part of.
Although the galaxies are separated by immense distances, it can sometimes happen that two or more galaxies in the same cluster begin to exert a strong gravitational force on each other, so as to bring them closer to the point where they collide.
