GRAVITY!
Elliptical galaxies are massive blobs of stars characterized by their round or ellipsoidal shapes. These galaxies are composed mainly of older stars and have little to no ongoing star formation activity.
Typically irregular galaxies have the oldest stars
In a galaxy, there are stars, the stars' planets, and the planets' moons. There are comets, asteroids, gas, dust, emptiness. You'll find nebula (star-forming regions) and black holes. In most galaxies, there is one supermassive black hole in the center that holds the entire galaxy together.
The universe contains all the stars and galaxies in existence. Stars are massive celestial bodies that emit light and heat, while galaxies are vast systems of stars, gas, dust, and dark matter bound together by gravity. Together, they make up the incredible tapestry of the cosmos.
An irregular luminous band of stars is called a "galaxy." Galaxies are massive systems of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. They come in various shapes and sizes and can contain billions to trillions of stars.
Gravity is the force responsible for the formation of the solar system, the movement of objects within the solar system, and holding together stars and galaxies. It is a fundamental force of nature that acts over large distances and is essential for understanding the structure of the universe.
Gravity plays a crucial role in galaxy formation and evolution. It acts as the force that pulls gas and dust together to form stars and holds together the structures of galaxies. Gravity also influences the motion of stars and other celestial bodies within a galaxy, shaping its overall structure and dynamics.
A large band of stars, gas, and dust particles hele together by gravitational force is called galaxy. Galaxies are really complex in nature consisting of billinns of stars. Some galaxies emit a comparatively small amount of radio radiations compared to the total radiations emitted and r called nosmal galaxies. Some galaxies are found to emit millions of times more radio waves compared to normal galaxies. They are called radio galaxies.
Gravity
Galaxies are made up of billions of stars, along with gas, dust, and dark matter. These components come together to form vast systems that are bound together by gravity.
Galaxies are vast collections of stars. So I guess you could say that a big group of stars forms a galaxy. Our galaxy has many big clusters of stars within it, so not all star clusters are galaxies. If you have a cluster of several million or billion (or trillion) stars surrounded by a lot of empty space, that is probably a galaxy.
A very large system of stars held together by gravity is called a galaxy. Galaxies can contain billions to trillions of stars, along with gas, dust, and dark matter. They come in various shapes, such as spiral, elliptical, and irregular. Our own Milky Way is an example of a spiral galaxy.