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==Types of stars according to Metallicity==

==Types of stars according to Metallicity==

'''Population I stars''' are stars that are considered to be the most metal-rich (or highest metallicity), our sun falls into this category. Although such stars may be as metal-poor as >-1 in comparison to the sun, many have more metallicity then our own sun.  Such stars tend to be found either in, or near the plane of a spiral galaxy such as our own [[Milky Way]].  Some of these stars are referred to as ''Extreme Population I stars'', found in the spiral arms, class O and B stars, T Tauri stars and other stars just entering the main sequence of stellar evolution are counted among these stars<ref>http://www.daviddarling.info/encyclopedia/P/PopI.html</ref>.

'''Population I stars''' are stars that are considered to be the most metal-rich (or highest metallicity), our sun falls into this category. Although such stars may be as metal-poor as >-1 in comparison to the sun, many have more metallicity then our own sun.  Such stars tend to be found either in, or near the plane of a spiral galaxy such as our own [[Milky Way]].  Some of these stars are referred to as ''Extreme Population I stars'', a classification reserved for what are believed to be the youngest stars, and are always found in the spiral arms.  Class O and B stars, T Tauri stars and other stars just entering the main sequence of stellar evolution are counted among these stars.<ref>http://www.daviddarling.info/encyclopedia/P/PopI.html</ref>.

'''Population II stars''' are metal-poor stars (negative values beyond -1), usually located in the bulge near to the center of spiral galaxies as well as the galactic halo.  Such stars are also common in Globular Clusters and make up the overwhelming number of the stellar population in elliptical galaxies.  These stars are the reasoned source of most of the elements in the periodic table<ref>http://www.daviddarling.info/encyclopedia/P/PopII.html</ref>.

'''Population II stars''' are metal-poor stars (negative values beyond -1), usually located in the bulge near to the center of spiral galaxies as well as the galactic halo.  Such stars are also common in Globular Clusters and make up the overwhelming number of the stellar population in elliptical galaxies.  These stars are considered to be older then Population I stars, and are the reasoned source of most of the elements in the periodic table<ref>http://www.daviddarling.info/encyclopedia/P/PopII.html</ref>.

'''Population III stars''' are essentially metal-free stars, although some have metals at the end of their lives.  Population III stars were considered to be extremely massive and hot but have not been directly observed. Indirect evidence of their existence has been found through looking at [[General theory of relativity|gravitationally lensed]]<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002ApJ...567..532H</ref>, and distant faint blue galaxies in the very distant universe<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003ApJ...596..797F</ref>.

'''Population III stars''' are essentially metal-free stars, although some have metals at the end of their lives.  Population III stars were considered to be extremely massive and hot but have not been directly observed. According to the Big Bang theory, these are the first hypothetical stars to have formed in the universe. Indirect evidence of their existence has been found through looking at [[General theory of relativity|gravitationally lensed]]<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002ApJ...567..532H</ref>, and distant faint blue galaxies in the very distant universe<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003ApJ...596..797F</ref>.

==Evolutionist Beliefs==

==Metallicity as a measurement of star age==

Evolutionists believe that the metallicity of such astronomical objects may offer clues to those objects' ages. According to their [[Big Bang|Big Bang theory]], when the universe first formed, it consisted mostly of hydrogen with a sizable proportion of helium; only trace amounts of [[lithium]] and [[beryllium]] are believed to have been created, with no heavier elements forming. Thus, they believe that older stars will have lower metallicity than younger stars, as all other elements were created through stellar and supernova nucleosynthesis.

The metallicity of such astronomical objects is one method astronomers use that may offer clues to those objects' ages. According to the [[Big Bang|Big Bang theory]], when the universe first formed, it consisted mostly of hydrogen with a sizable proportion of helium; only trace amounts of [[lithium]] and [[beryllium]] are believed to have been created, with no heavier elements forming. Based on this model, older stars will have lower metallicity than younger stars, as all other elements were created through Stellar and Supernova nucleosynthesis.

[[Category:Astronomy]]

[[Category:Astronomy]]