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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 usual endpoint of stellar evolution is the formation of a compact star.. All active stars will eventually come to a point in their evolution when the outward radiation pressure from the nuclear fusions in its interior can no longer resist the ever-present gravitational forces.
At a distance of 14.1 light-years it is the third closest of its type of star after Sirius B and Procyon B, in that order. [ 9 ] [ 10 ] Discovered in 1917 by Dutch–American astronomer Adriaan van Maanen , [ 11 ] Van Maanen 2 was the third white dwarf identified, after 40 Eridani B and Sirius B, and the first solitary example.
For stars with similar metallicity to the Sun, the theoretical minimum mass the star can have, and still undergo fusion at the core, is estimated to be about 75 M J. [ 13 ] [ 14 ] When the metallicity is very low, however, a recent study of the faintest stars found that the minimum star size seems to be about 8.3% of the solar mass, or about 87 ...
In massive stars (greater than about 1.5 M ☉), the core temperature is above about 1.8×10 7 K, so hydrogen-to-helium fusion occurs primarily via the CNO cycle. In the CNO cycle, the energy generation rate scales as the temperature to the 15th power, whereas the rate scales as the temperature to the 4th power in the proton-proton chains. [2]
Westerhout 51 nebula in Aquila - one of the largest star factories in the Milky Way (August 25, 2020). Star formation is the process by which dense regions within molecular clouds in interstellar space—sometimes referred to as "stellar nurseries" or "star-forming regions"—collapse and form stars. [1]
In astronomy, the initial mass function (IMF) is an empirical function that describes the initial distribution of masses for a population of stars during star formation. [1] IMF not only describes the formation and evolution of individual stars, it also serves as an important link that describes the formation and evolution of galaxies. [1]
Gravitational collapse of a massive star, resulting in a Type II supernova. Gravitational collapse is the contraction of an astronomical object due to the influence of its own gravity, which tends to draw matter inward toward the center of gravity. [1] Gravitational collapse is a fundamental mechanism for structure formation in the universe.