Free Essay Describing Galaxies

Describe the structure of the five common galaxy types and the factors that contributed to their formation

Galaxies were classified as a structure that involves a million stars which are held together with dust and gas by the help of a gravitational pull. Galaxies consist of five common forms which are Elliptical, Irregular, Cartwheel, Spiral, and Barred Spiral. All the types of galaxies have different structures which they form. Elliptical galaxies were classified into two elliptical galaxies. These are the E0 and E7. Elliptical galaxies were formed in such a way that they appear to be like stretched circles. The galaxy is made mostly of old stars. As a result of collisions between the galaxies. Milky Way and the Andromeda galaxies collide through which the little known elliptical galaxy were formed.

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Elliptical Galaxies

E0 types of elliptical galaxies were known to produce an almost perfect circle. The E7 elliptical galaxy is longer in size and broader too. In earth' viewpoint, an individual would not be able to see the shape of the E7 elliptical galaxy as described in books. The shape of the E7 elliptical galaxy is known to hide its form due to the way it rests on the surface of the sky (Falcon-Barroso & Knapen, 2012). According to the astronomers, elliptical galaxies were difficult to view as compared to the spiral galaxies due to their shape. Elliptical galaxies were considered to dim whereas the spiral galaxies were bright.

Spiral Galaxies

The Spiral galaxies were formed as a result of gas clouds moving into density waves. Scientists have been able to come up with three different hypothesis regarding the formation of spiral galaxies. First is the collapse of gas clouds which is known as the primordial collapse. The other assumption is the merging of small galaxies which form one large galaxy. This formation were referred to as the hierarchical clustering (Falcon-Barroso & Knapen, 2012). The third is through the formation of spiral arms and bar which is known as secular evolution. The bulges and halos were often formed through the collapse of individual gases. After the collapse of different gases, the secular evolution also seems to appear with the help of the spiral bulges (Falcon-Barroso & Knapen, 2012).

Barred- Spiral and Irregular Galaxies

Unlike the spiral galaxy, the barred spiral galaxy has a center-bar shaped structure that holds up the stars. The bars have been studied to affect the motion of the stars. The barred spiral were formed when the spiral galaxy bar becomes unstable. What makes the spiral bars is unknown though certain theories have linked the imbalance to occur as a result of an interaction of stars which tend to rotate in different directions (Falcon-Barroso & Knapen, 2012). Irregular galaxies were formed when two galaxies collide thus giving them unnoticeable shape. The Irregular galaxies are always considered to be smaller as compared to the other forms of galaxies. Irregular gases also get their shape as a result of small, young galaxies which have not yet gotten a shape.

Cartwheel Galaxy

The Cartwheel galaxy was identified through its ring structure. The galaxy was formed as a result of two galaxies colliding. The cartwheel galaxy has shapes of waves which are similar to those that appear when an object was thrown to a lake (Falcon-Barroso & Knapen, 2012). The waves formed appear to be as a result of small galaxies that pass around the big galaxies sweeping away the gases.

Reference

Falcon-Barroso, J., & Knapen, J. (2012). Secular evolution of galaxies. Cambridge University, Press