Constellations have been sorted by their optical configuration for ease of identification. Astronomers use the morphological procedure of classification to group the galaxies. This method involves the assessment of the optical features of the galaxy. This method also includes various schemes the most distinguished is the Hubble sequence. Computation methods have made optical classification easier and have classified constellations into four main groups.
Spiral galaxies have the characteristic of a flat rotating disk. They also have a pivotal protuberance with twirl arms around it. They rotate with a maximum speed of a hundred miles each second. This speed makes matter to form a noticeable spiral shape. The protuberance constitutes of old darker stars. The twirl constitutes of dust and a lot of gas.
They are symbolized by an extensive spherical shape. Unlike the Spiral Galaxies, Elliptical galaxies lack a swelling at the central region. The brightness of the galaxy diminishes towards the exterior edges. Old reddish stars are responsible for the light in these galaxies. They can be nearly round or take the shape of a cigar and vary in size.
This type of constellation has no definite shape but always in a constant motion similar to all other constellations. They don’t have a central bulge. There are three forms of irregular galaxies; Irr I, Irr II and DIrr III all with distinctive characteristics. Gravity from large clouds like Magellanic Clouds is responsible for the irregular shape in this type of galaxies.
Barred Spiral Galaxies
The only difference between Barred Spiral constellations and Spiral constellations is the bright stars at the centre of the protuberance. The blaze produced extends into the disk. They are further classified into Types A, B and C.
There are also other minor forms of galaxies. Different constellations are still being discovered. It is important to do regular research to get updated.