Abstract

One of the biggest challenges for astronomers today is understanding how galaxies form. Observations from the Hubble Space Telescope and instruments on Earth show that the first galaxies formed as early as 1 billion years after the Big Bang, which probably occurred between 13 and 14 billion years ago.The Milky Way may contain the remains of several smaller galaxies that it has swallowed up throughout its long life.

When we look at the stars in the sky at night, we are seeing other stars in the Milky Way. If it is very dark and we are far from the lights of the city and the houses, we can even see how the strips of dust of the Milky Way expand in the sky, but there are many other galaxies besides our own.The types of galaxies are:

Elliptical Galaxies

Some galaxies have a complete globular profile with a bright nucleus.

These galaxies, called ellipticals, contain a large population of old stars, usually little gas and dust, and some newly formed stars. In the photo, the elliptical Sombrero Galaxy, M104. In elliptical galaxies the concentration of stars decreases from the nucleus, which is small and very bright, towards their edges.

Spiral Galaxies

The spiral galaxy. It was classified with this name because of the spiral shape in which the arms of the nucleus come out, like our Milky Way

• Barred Spiral Galaxy: These galaxies are similar to the previous ones, except that the arms emerge from a series of stars and not from the center.

• Elliptical galaxy: Unlike the others, these galaxies are identified by their shape that goes from round to oval, and they do not have a central bulge like the spiral galaxy

Irregular Galaxies

An irregular galaxy is a galaxy that does not fit into any classification of galaxies in the Hubble sequence. An Irr-I galaxy is an irregular galaxy that shows some structure, but not enough to fit neatly into the Hubble sequence classification. Some irregular galaxies are small spiral galaxies distorted by the gravity of a much larger neighbor.

Lenticular galaxies

Lenticular galaxies are a transition group between elliptical and spiral galaxies, and are divided into three subgroups: SO1, SO2, and SO3. They have a disc, a very important central condensation and an extensive envelope.

They include the barred lenticulars (SBO), which comprise three groups: in the first (SBO-1), the bar is wide and diffuse; in the second (SBO-2) it is more luminous in the extremities than in the center; and in the third (SBO-3) it is already very bright and well defined.

components of a galaxy

By observing a galaxy you can identify structures such as the following, which are present in the Milky Way, which has been taken as a model because it is the best studied:

Disc and halo

The two basic structures of our galaxy are the disk and the halo. The disk is in the middle plane defined by the galaxy and contains a large amount of interstellar gas that gives rise to new stars. It also contains old stars and open clusters – a loosely structured grouping of stars, the Sun is located in the galactic disk of the Milky Way, on the plane of symmetry and like all the stars in the disk, orbits the galaxy following a trajectory approximately circular and perpendicular to the axis of galactic rotation. It takes about 250 million years to complete an orbit The halo coats the galaxy with a less dense spheroidal volume, as it is a region with much less dust and gas. It contains globular clusters, stars grouped by the action of gravity and much older than that of the disk, individual stars and also the so-called dark matter.

• It is concluded that galaxies are systems full of stars, planets, cosmic dust, etc. That they can be of different shapes and sizes, it is also known that there are thousands of millions of them, and we still have a long way to go to discover the infinite universe.

• As a group we have learned more about the galaxies. And it was learned that galaxies are like seas of light in a vacuum universe formed shortly after the explosion of the big bang, when the universe was young.