Formation of the sun
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Sun Formation Timeline and Nebular Theory
The Sun formed about 4.6 billion years ago from the gravitational collapse of a region within a giant molecular cloud, often referred to as a nebula, in one of the spiral arms of the Milky Way galaxy Ke2023Zhong2019Kondratenko2018+3 MORE. This process is described by the nebular theory, which is the most widely accepted explanation for the formation of the Sun and the solar system Zhong2019Kondratenko2018Nimmo1986. As the cloud collapsed, most of its material gathered at the center to form the Sun, while the remaining material flattened into a disk that eventually formed the planets Kondratenko2018Nimmo1986Gargaud2012.
Birth Environment and Star Cluster Formation
Evidence suggests that the Sun likely formed as part of a star cluster, rather than in isolation Nimmo1986Pfalzner2020Desch2024. The type of cluster—whether a high-mass, extended association or an intermediate-mass, compact cluster—would have influenced the early solar system’s structure and the distribution of material within it Pfalzner2020Desch2024. The Sun’s protoplanetary disk was exposed to ultraviolet radiation and stellar winds from nearby stars, which affected its evolution and the materials it inherited, such as certain radionuclides .
Collapse and Ignition of Nuclear Fusion
The collapse of the molecular cloud core was rapid on a geological timescale, possibly taking only tens of thousands of years Brennecka2021Gargaud2012. As the core’s temperature rose to about 10 million Kelvin, nuclear fusion of hydrogen into helium began, marking the Sun’s transition into a true star Zhong2019Gargaud2012. This fusion process continues today, powering the Sun and producing the energy that supports life on Earth Ke2023Zhong2019.
Early Solar System and Protoplanetary Disk
After the Sun ignited, the leftover material in the disk around it began to coalesce into planets, moons, and other solar system bodies Kondratenko2018Nimmo1986Gargaud2012. Meteorites and the structure of the current solar system provide clues about these early stages, indicating that the solar system’s formation history is similar to that of other star systems observed today .
Conclusion
The Sun’s formation began with the collapse of a molecular cloud about 4.6 billion years ago, likely within a star cluster. The process was rapid, leading to the ignition of nuclear fusion and the birth of the Sun. The remaining material formed the planets and other bodies of the solar system. The Sun’s early environment, including nearby stars and radiation, played a significant role in shaping the solar system as we know it today Ke2023Zhong2019Kondratenko2018+5 MORE.
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