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It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a balanced equilibrium by the fusion of hydrogen into helium at its core, releasing this energy from its outer photosphere. Astronomers classify it as a G-type main ...
Whether the presence of the isotopes iron-60 and aluminium-26 can be interpreted as a sign of a birth cluster containing massive stars is still under debate. If the Sun was part of a star cluster, it might have been influenced by close flybys of other stars, the strong radiation of nearby massive stars and ejecta from supernovae occurring close by.
The nebula nearest to the Sun where massive stars are being formed is the Orion Nebula, 1,300 light-years (1.2 × 10 16 km) away. [11] However, lower mass star formation is occurring about 400–450 light-years distant in the ρ Ophiuchi cloud complex .
Of the main-sequence star types, stars more massive than 1.5 times that of the Sun (spectral types O, B, and A) age too quickly for advanced life to develop (using Earth as a guideline). On the other extreme, dwarfs of less than half the mass of the Sun (spectral type M) are likely to tidally lock planets within their habitable zone, along with ...
The evolution of binary star and higher-order star systems is intensely researched since so many stars have been found to be members of binary systems. Around half of Sun-like stars, and an even higher proportion of more massive stars, form in multiple systems, and this may greatly influence such phenomena as novae and supernovae, the formation ...
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 A mass-radius plot ...
Once the surrounding dust and gas is blown away, the remaining stars become unbound and begin to drift apart. [7] It is believed that the majority of all stars in the Milky Way were formed in OB associations. [7] O class stars are short-lived, and will expire as supernovae after roughly one to fifteen million years, depending on the mass of the ...
A Sun-like star usually takes approximately 1 million years to form, with the protoplanetary disk evolving into a planetary system over the next 10–100 million years. [ 2 ] The protoplanetary disk is an accretion disk that feeds the central star. [ 3 ]