The Different Types of Galaxies
Our universe has broad classification of four identified types of galaxies. All these galaxies comprise of hot starts, planets, moons, gas and dust bound together with gravitational forces from various sources. The type of galaxies identified and broadly classified are based on their shapes, thus making it easy to identify them. Although there are nearly infinite number of galaxies in universe but formation of galaxies if rare event and these are formed by combination og gasses, dust, matter get acted upon by gravitational forces.
Each of these galaxy has their own collection of stars, various planets, moons, dust & ice particles, black holes, nebulae, neutron stars, asteroids, comets, and dark matter. Our galaxy fall in the category of barred spiral galaxy and is lovingly named as the Milky Way, It has massive spiral arms with a bulging disk and supermassive black hole i in the center. Just like planets and stars, even galaxies are in constant motion. The entire universe is made of varied galaxies that are the basic candidates of the universe. The universe hold large influx and diversity of galaxies, some are very simple and basic while others are extremely complex.
Hubble's Principle Schemes
In 1926, Edwin Hubble devised a classification of the galaxies. The diagrammatic representation of Hubble's Scheme is shaped like a tuning fork and is commonly referred to as the Hubble Tuning Fork. Hubble placed the different types of galaxies in a logical and agreed evolutionary order. The handle of the tinning fork he placed the elliptical galaxies, and on the two tines, contained the spiral galaxies. Edwin Hubble noticed, each type of galaxy had immense variations.
Spiral Galaxies
Spiral galaxies can be easily identified by observing three components common to all spiral galaxies. A spiral galaxy has a circular disk, a slight bulge, and a halo surrounding. The centre of the galaxy is like a nucleus, containing a sphere shaped bulge that accommodates old stars and is free of dust and gas. The spiral or circular shape of the galaxy forms the disk. Arms of the spiral galaxy originate in the disk and are where new stars will form in a galaxy. Spiral galaxies with no arm are termed as Lenticular.
Barred Spiral Galaxies
Barred spiral galaxies share the common characteristics, features and functions as regular spiral galaxies, but they also have a collection of bright stars that reside along the center of the bulge, and extend into the disk. The bright bulge has very little activity here and contains mostly veteran older red stars. The bar and arms have lots of activity including the formation of new stars.
Elliptical Galaxies
Elliptical galaxies can be identified by their elongated spherical shape and the absence of nucleus or bulge at the center. Although there is no nucleus, the galaxy is still brighter in the center and becomes less bright transitioning outward of the galaxy. It is believed, there is a great deal of the mass in an elliptical galaxy, due to the presence of a central black hole. These galaxies lack gasses and dust to form new stars.
Irregular Galaxies
Irregular galaxies are collection of cosmic dust and gas, stars, neutron stars, nebulous formations, black holes and other elements common to all galaxies. Irregular galaxies as the name suggest, they have no definite shape, but like all galaxies, they are in constant motion, moving outward and away from the center of our universe. Irregular galaxies are further classified into two types: Im and IO. Im galaxies show signs of spiral galaxies and IO galaxies are very random and chaotic in their shape.
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