Population I stars are relatively young stars that are found primarily in the spiral arms of galaxies, including the Milky Way. They are metal-rich, meaning they contain a higher abundance of elements heavier than hydrogen and helium, which is a result of stellar evolution and supernovae enriching the interstellar medium. These stars typically have a higher temperature and luminosity compared to older stars, and they often include main-sequence stars, giants, and supergiants. Their formation is closely associated with ongoing star formation and the presence of interstellar gas and dust.
Population 1 stars are metal rich stars. See related question.
Population 1 stars are luminous. They include the Sun and are hot and young stars. These types are usually found in spiral galaxies. Population 2 stars are found in nucleuses of galaxies and globular galaxies. These stars are older and usually cooler than the population 1 ones.
Population I stars
Population II stars are the oldest in our Milky Way. Population III stars were the first stars in the Universe, but have yet to be discovered. See related question
Population I stars are young and luminous like the Sun. Population II stars consist of globular clusters that are generally much older.
Population II stars are lower in "metals" than population I stars. By metals, astronomers mean anything other than hydrogen and helium.
Population I stars have more metals (heavier elements), and are generally younger, than the Population II stars. It is postulated that there are still older Population III stars, that have even less metals and are even older, but none have been discovered yet.
Population I stars
The oldest stars are classified as population III stars [See related question]
The oldest stars are classified as population III stars [See related question]
The so-called "Population I" stars are found in the galactic suburbs, which is where we live. Population II stars are concentrated toward the galactic bulge.
The hottest stars. Generally, globular clusters contain mainly old stars, population II stars