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Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution
The following is a list of particularly notable actual or hypothetical stars that have their own articles in Wikipedia, but are not included in the lists above. BPM 37093 — a diamond star Cygnus X-1 — X-ray source
These names of stars that have either been approved by the International Astronomical Union or which have been in somewhat recent use. IAU approval comes mostly from its Working Group on Star Names, which has been publishing a "List of IAU-approved Star Names" since 2016. As of April 2022, the list included a total of 451 proper names of stars.
The age of the oldest known stars approaches the age of the universe, about 13.8 billion years. Some of these are among the first stars from reionization (the stellar dawn), ending the Dark Ages about 370,000 years after the Big Bang. [1] This list includes stars older than 12 billion years, or about 87% of the age of the universe.
In cosmology, the study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies.
The age of the universe as estimated from the Hubble expansion and the CMB is now in agreement with other estimates using the ages of the oldest stars, both as measured by applying the theory of stellar evolution to globular clusters and through radiometric dating of individual Population II stars. [114]
List of the largest known stars in the Magellanic Clouds Star name Solar radii (Sun = 1) Galaxy Method [a] Notes Theoretical limit of star size (Large Magellanic Cloud) ≳1,550 [11] L/T eff: Estimated by measuring the fraction of red supergiants at higher luminosities in a large sample of stars. Assumes an effective temperature of 3,545 K.
This obscure terminology is a hold-over from a late nineteenth century model of stellar evolution, which supposed that stars were powered by gravitational contraction via the Kelvin–Helmholtz mechanism, which is now known to not apply to main-sequence stars. If that were true, then stars would start their lives as very hot "early-type" stars ...