In astronomy and physical cosmology, the term "metal" or metal-rich is used to refer to any element heavier than hydrogen and helium. For example, a nebula that was rich in carbon compounds would be called "metal-rich", even though carbon is not considered a metal in other contexts. Elements heavier than hydrogen and helium and lithium are distinguished by having been created by nuclear fusion since the original formation of the universe.

The Earth's Sun is an example of a metal-rich star.

The term Metal-rich is also called Population I stars.

Population I stars are the young star population, having formed in the last few billion years, and are generally found in the disk of the Galaxy. Generally, the youngest stars are found further in, and intermediate population I stars are further out, etc. The Sun is considered an intermediate population I star. Population I stars have regular elliptical orbits of the galactic centre. They are considered to be metal-rich because they have formed after the remnants of population II stars (metals) were present in the inter-stellar medium.

Sources

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Page 593-In Quest of the Universe Fourth Edition Karl Kuhn Theo Koupelis. Jones and Bartlett Publishers Canada. 2004. ISBN 0-7637-0810-0

See also

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• Abundance of the chemical elements
• Metal-poor or Population II stars
• Metallicity
• Population III stars
• Stellar population

Population I stars | Stars by metallicity