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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 observed upper limit for a main-sequence star is 120–200 M ☉. [34] The theoretical explanation for this limit is that stars above this mass can not radiate energy fast enough to remain stable, so any additional mass will be ejected in a series of pulsations until the star reaches a stable limit. [35]
Substellar objects like brown dwarfs do not have enough mass to fuse hydrogen and helium, hence do not undergo the usual stellar evolution that limits the lifetime of stars. A substellar object with a mass just below the hydrogen-fusing limit may ignite hydrogen fusion temporarily at its center.
The mass/luminosity relationship can also be used to determine the lifetime of stars by noting that lifetime is approximately proportional to M/L although one finds that more massive stars have shorter lifetimes than that which the M/L relationship predicts. A more sophisticated calculation factors in a star's loss of mass over time.
The most luminous known stars have absolute magnitudes of roughly −12, corresponding to 6 million times the luminosity of the Sun. [188] Theoretically, the least luminous stars are at the lower limit of mass at which stars are capable of supporting nuclear fusion of hydrogen in the core; stars just above this limit have been located in the ...
A star system 3,000 light-years away from Earth is predicted to become visible to the naked eye this year — likely a once-in-a-lifetime viewing opportunity, as the phenomenon only occurs roughly ...
What researchers are calling a "Once-in-a-lifetime event," is a nova, or explosion, between two suns 3,000 lightyears away. 'Once-in-a-lifetime event': Explosion in space to look like new star ...
The trace amounts of heavier elements were and are produced within stars via stellar nucleosynthesis and ejected as the stars pass beyond the end of their main sequence lifetime. Higher density regions of the interstellar medium form clouds, or diffuse nebulae , [ 3 ] where star formation takes place. [ 4 ]