right|thumb|upright=1.4|Artist's conception of the spiral structure of the Milky Way showing Baade's general population categories. The blue regions in the spiral arms are composed of the younger population I stars, while the yellow stars in the central bulge are the older population II stars. In reality, many population I stars are also found mixed in with the older population II stars.
In 1944, Walter Baade categorized groups of stars within the Milky Way into stellar populations.
In the abstract of the article by Baade, he recognizes that Jan Oort originally conceived this type of classification in 1926. - a candidate Population II star in the ultrafaint dwarf galaxy Pictor II was found to have iron levels < 1/43,000 and calcium levels < 1/160,000 of the sun, but carbon > 3000x solar levels. Such stars are likely to have existed in the very early universe (i.e., at high redshift) and may have started the production of chemical elements heavier than hydrogen, which are needed for the later formation of planets and life as we know it.
On 27 October 2025, astronomers published a paper in the Astrophysical Journal Letters, reporting that LAP1-B might be the first observed cluster of population III stars, with a redshift of z=6.6 and with a total mass of up to 2700 solar masses, that seemingly meets the three most critical criteria for a star to be considered as a population III star.
See also
- Lists of astronomical objects
- Lists of stars
- Peekaboo Galaxy
Notes
References
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