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The hydrogen fuel at the core will finally be exhausted in five billion years, when the Sun will be 67% more luminous than at present. Thereafter, the Sun will continue to burn hydrogen in a shell surrounding its core until the luminosity reaches 121% above the present value.
The Sun reaches the top of the red-giant branch of the Hertzsprung–Russell diagram, achieving its maximum radius of 256 times the present-day value. [116] In the process, Mercury, Venus and Earth are likely destroyed. [112] 8 billion The Sun becomes a carbon–oxygen white dwarf with about 54.05% of its present mass.
The Sun is a main-sequence star, and, as such, generates its energy by nuclear fusion of hydrogen nuclei into helium. In its core, the Sun fuses 620 million metric tons of hydrogen and makes 616 million metric tons of helium each second. The fusion of lighter elements in stars releases energy and the mass that always accompanies it.
The Sun is a burning plasma that has reached fusion ignition, meaning the Sun's plasma temperature is maintained solely by energy released from fusion. The Sun has been burning hydrogen for 4.5 billion years and is about halfway through its life cycle. [1]
The Sun's core temperature, at which PP is more efficient 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 .
Fusing four free protons (hydrogen nuclei) into a single alpha particle (helium nucleus) releases around 0.7% of the fused mass as energy, [68] so the Sun releases energy at the mass–energy conversion rate of 4.26 billion kg/s (which requires 600 billion kg of hydrogen [69]), for 384.6 yottawatts (3.846 × 10 26 W), [5] or 9.192 × 10 10 ...
At the Sun's core temperature of 15.5 million K the PP process is dominant. The PP process and the CNO process are equal at around 20 MK. [1] Scheme of the proton–proton branch I reaction. The proton–proton chain, also commonly referred to as the p–p chain, is one of two known sets of nuclear fusion reactions by which stars convert ...
The expanding Sun is expected to vaporize Mercury as well as Venus, and render Earth and Mars uninhabitable (possibly destroying Earth as well). [31] [32] Eventually, the core will be hot enough for helium fusion; the Sun will burn helium for a fraction of the time it burned hydrogen in the core. The Sun is not massive enough to commence the ...