"Star generation" redirects here. For the process by which molecular clouds collapse and form stars, see Star formation.
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.[1]
Baade observed that bluer stars were strongly associated with the spiral arms, and yellow stars dominated near the central galactic bulge and within globular star clusters.[2] Two main divisions were defined as population I and population II, with another newer, hypothetical division called population III added in 1978.
Among the population types, significant differences were found with their individual observed stellar spectra. These were later shown to be very important and were possibly related to star formation, observed kinematics,[3] stellar age, and even galaxy evolution in both spiral and elliptical galaxies. These three simple population classes usefully divided stars by their chemical composition or metallicity.[4][5][3]
By definition, each population group shows the trend where decreasing metal content indicates increasing age of stars. Hence, the first stars in the universe (very low metal content) were deemed population III, old stars (low metallicity) as population II, and recent stars (high metallicity) as population I.[6] The Sun is considered population I, a recent star with a relatively high 1.4% metallicity. Note that astrophysics nomenclature considers any element heavier than helium to be a "metal", including chemical non-metals such as oxygen.[7]
^Cite error: The named reference Baade-1944 was invoked but never defined (see the help page).
^Cite error: The named reference Shapley-1977 was invoked but never defined (see the help page).
^ abCite error: The named reference Gibson-etal-2013 was invoked but never defined (see the help page).
^Cite error: The named reference Kunth-Östlin-2000 was invoked but never defined (see the help page).
^Cite error: The named reference schonrich2009 was invoked but never defined (see the help page).
^Cite error: The named reference Byant-2005 was invoked but never defined (see the help page).
^Cite error: The named reference metal was invoked but never defined (see the help page).
and 27 Related for: Stellar population information
Walter Baade categorized groups of stars within the Milky Way into stellarpopulations. In the abstract of the article by Baade, he recognizes that Jan...
In astrophysics, stellar nucleosynthesis is the creation of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred...
Hertzsprung–Russell diagram. These coronae can be detected using X-ray telescopes. Some stellar coronae, particularly in young stars, are much more luminous than the Sun's...
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is...
Vanhollebeke, E.; Groenewegen, M. A. T.; Girardi, L. (April 2009). "Stellarpopulations in the Galactic bulge. Modelling the Galactic bulge with TRILEGAL"...
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few...
In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses...
different populations of stars. These became commonly known as population I (metal-rich) and population II (metal-poor) stars. A third, earliest stellar population...
A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars...
affects the strength of its stellar wind. Older, population II stars have substantially less metallicity than the younger, population I stars due to the composition...
Stellar parallax is the apparent shift of position (parallax) of any nearby star (or other object) against the background of distant stars. By extension...
A stellar black hole (or stellar-mass black hole) is a black hole formed by the gravitational collapse of a star. They have masses ranging from about 5...
Young stellar object (YSO) denotes a star in its early stage of evolution. This class consists of two groups of objects: protostars and pre-main-sequence...
black holes, neutron stars are the smallest and densest known class of stellar objects. Neutron stars have a radius on the order of 10 kilometers (6 mi)...
a stellar component (composed of most of the galaxy's stars) and a gaseous component (mostly composed of cool gas and dust). The stellarpopulation of...
Stellar structure models describe the internal structure of a star in detail and make predictions about the luminosity, the color and the future evolution...
A stellar core is the extremely hot, dense region at the center of a star. For an ordinary main sequence star, the core region is the volume where the...
Cassisi, Santi (2005). "Evolution of Stars and StellarPopulations". Evolution of Stars and StellarPopulations: 400. Bibcode:2005essp.book.....S. Pols, Onno...
1193 is usually classified as a Trumpler type II3m, indicating its stellarpopulation have a wide range of brightness, from very bright to faint stars and...
In astronomy, stars have a variety of different stellar designations and names, including catalogue designations, current and historical proper names...
within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars. As a branch...
In stellar evolution, an isochrone is a curve on the Hertzsprung-Russell diagram, representing a population of stars of the same age but with different...
An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists...
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. The stellar atmosphere...
reveals multiple stellarpopulations as indicated by the presence of closely separated curves, each corresponding to a distinct population of stars with...
often the endpoints of stellar evolution and, in this respect, are also called stellar remnants. The state and type of a stellar remnant depends primarily...