how much the population of stars in the galaxy?

( Galaxy / Google Image)

Save as objects in the universe have different characteristics such as size, shape, mass, luminosity and age. There is a relationship between the characteristics of the star with his place in the galaxy. The young star around several million years of age, illuminating the spiral arms of the galaxy. These stars are stars that are brighter and more massive and occupies the blue group in the main sequence. Strong radiation illuminates interstellar gas clouds such as fog Horse Head (horsehead nebula). The stars are about half the age of the age of several billion years, distributed evenly throughout the dish, while older stars with ages of more than 10 billion years old, are scattered around the disk that appears in the halo and core regions (regional center of the galaxy). Of stars that make up this galaxy, roughly half of which is a binary star system (binary) or many star systems where two or more stars are there in the system orbiting each other caused by the pull of gravity. Many stars are also bound together by gravity to form groups (clusters) that contain hundreds of thousands of stars in the region of hundreds of light years or more. The Milky Way contains 400 billion stars with a range of about 100,000 light years.

( Star / Google Image)

Star maha very bright giant and main sequence stars with high luminosity (class O and B) and stars Chepeid type I found in the area of ​​interstellar matter, namely the spiral arms of the galaxy. While the types of other stars no relation place in galaxies such as planetary nebulae, nova, Chepeid type II, Lyrae variable stars, and globular clusters. The main sequence star class F and M, as well as red giants and white dwarfs are in all parts of the galaxy. Similarly, the chemical composition, there is a difference from the stars a different position in the galaxy. The sun and other stars in relation between interstellar material from the spiral arms have heavy elements around 1-4% of the total mass of the star, while the galactic halo stars and globular clusters have a heavy element that is much less of about 0.1 to 0.01 of sun. The stars that inhabit the spiral arms are often said to include population I, while those in other places in the galaxy said to include populations II. Population I consists of stars with different ages, whereas the population II is composed entirely of old stars perhaps the formation of the Milky Way galaxy's age.