The term galactic halo is used to denote an extended, roughly spherical component of a galaxy, which extends beyond the main, visible component. A galaxy is a massive gravitationally bound system consisting of Stars an Interstellar medium of gas and dust, and Dark matter It can refer to any of several distinct components which share these properties:

• the galactic spheroid (stars)
• the galactic corona (hot gas, i. A spiral galaxy is a Galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth The terms galactic corona and gaseous corona have been used in the first decade of the Twenty-first century to describe a hot Ionised gaseous component e. a plasma)
• the dark matter halo

The distinction between the halo and the main body of the galaxy is clearest in spiral galaxies, where the spherical shape contrasts with the flat disc. In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound Most of the mass of any galaxy is dominated by a component concentrated at the centre of the galaxy but dominating its dynamics throughout known as the Dark matter halo. A spiral galaxy is a Galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the A disc is a component of Disc galaxies, such as Spiral galaxies, or Lenticular galaxies. In an elliptical galaxy, there is no sharp transition between the body of the galaxy and the halo. An elliptical galaxy is a Galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble (whose name was dedicated

See also

• Galaxy formation and evolution
• Galactic coordinate system
• Galactic bulge
• Disc galaxy
  • Spiral arm
• Galactic spheroid
• Galactic corona

The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning the formation of the first galaxies the way The galactic coordinate system is a Celestial coordinate system which is centered on the Sun and is aligned with the apparent center of the Milky Way galaxy In Astronomy, a bulge is a tightly packed group of Stars The term almost exclusively refers to the central group of stars found in most spiral galaxies. Disc galaxies are galaxies which have discs, a flattened circular volume of stars A spiral galaxy is a Galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the A spiral galaxy is a Galaxy belonging to one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work “The Realm of the The terms galactic corona and gaseous corona have been used in the first decade of the Twenty-first century to describe a hot Ionised gaseous component

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