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These stars are often observed as a red clump of stars in the colour-magnitude diagram of a cluster, hotter and less luminous than the red giants. Higher-mass stars with larger helium cores move along the horizontal branch to higher temperatures, some becoming unstable pulsating stars in the yellow instability strip (RR Lyrae variables ...
Horizontal branch. The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun 's. Horizontal-branch stars are powered by helium fusion in the core (via the triple-alpha process) and by hydrogen fusion (via the CNO cycle) in a shell surrounding the core.
The main sequence is visible as a prominent diagonal band from upper left to lower right. This plot shows 22,000 stars from the Hipparcos Catalog together with 1,000 low-luminosity stars (red and white dwarfs) from the Gliese Catalogue of Nearby Stars. In astronomy, the main sequence is a classification of stars which appear on plots of stellar ...
Stellar population. 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 ...
Some red supergiants undergo blue loops where they temporarily increase in temperature before returning to the red supergiant state. This depends on the mass, rate of rotation, and chemical makeup of the star. While many red supergiants will not experience a blue loop, some can have several. Temperatures can reach 10,000K at the peak of the ...
Stellar nucleosynthesis. In astrophysics, stellar nucleosynthesis is the creation of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred since the original creation of hydrogen, helium and lithium during the Big Bang. As a predictive theory, it yields accurate estimates of the observed abundances of ...
Stellar isochrone. 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 mass. [1] The Hertzsprung-Russell diagram plots a star's luminosity against its temperature, or equivalently, its color. Stars change their positions on the HR diagram ...
A star-forming region in the Large Magellanic Cloud. A star is a luminous spheroid of plasma held together by self-gravity. [1] The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light.