What is a Galaxy and how many different

What is a Galaxy and, how many different kinds are there Joson Anjo C. Casillan VII- Amorsolo

What is a galaxy • • • Massive Gravitationally bound Stars Stellar remnants Dust and dark matter

Stellar Remnants • • White dwarfs Neutron stars Other exotic dense stars Black holes

Stellar evolution • The cycle of stars • Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime.

How many different kinds of galaxy are there • • • Elliptical Spiral Barred spiral Irregular Peculiar

Elliptical • An elliptical galaxy is a type of galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile.

Spiral • Spiral galaxies consist of a flat, rotating disc containing stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters.

Barred spiral • A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in approximately twothirds of all spiral galaxies.

Irregular • An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy.

Peculiar • A peculiar galaxy is a galaxy which is unusual in its size, shape, or composition.

References • • http: //www. apodnasa. gov http: //www. newscientist. com http: //ibp. fieldofscience. com http: //en. wikipedia. com