magazinessite.blogg.se - Spiral galaxy facts

This indicates that the bulges and halos of spiral galaxies probably formed through the primordial collapse of individual gas clouds early in the history of the Universe.

The bulge and halo of the Milky Way (and other Sa and Sb galaxies) are composed mostly of old stars. Secular evolution processes are thought to be responsible for the formation of young and intermediate age stars such as this in the bulges of spiral galaxies. The Arches is a young (2 million year old) cluster located in the centre of the bulge of the Milky Way. In particular, the formation of spiral galaxies is thought to be a complex process in which the stellar halo, bulge and disks are formed at different times and through different mechanisms. The degree to which each of these processes contributes to the formation of any particular galaxy is thought to depend on the galaxy’s Hubble type. secular evolution: formation as a result of internal processes, such as the actions of spiral arms and bars.hierarchical clustering: the formation of large galaxies through the merging of many smaller ones.

primordial collapse: the collapse of individual gas clouds early in the history of the Universe.

Since our own galaxy is a spiral, most of our understanding of spiral galaxy formation comes from studies of the stellar populations within the Milky Way.Īlthough the formation of galaxies is not fully understood, astronomers have identified the three key processes involved: The process of unravelling the formation history of galaxies (also referred to as galactic archaeology) depends largely on the measurement of the ages of stellar populations contained within the galaxies.