Baryonic matter primarily consists of protons and neutrons, which make up most of the ordinary matter we encounter. The most abundant types of baryonic matter in the universe include:
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Hydrogen: This is the most abundant element in the universe, making up about 75% of the normal (baryonic) matter. It exists primarily in the form of hydrogen atoms, but also as ionized hydrogen (protons).
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Helium: The second most abundant element, helium comprises about 25% of baryonic matter. It was primarily produced during the Big Bang nucleosynthesis.
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Other Light Elements: Trace amounts of other light elements such as deuterium (a hydrogen isotope), lithium, and beryllium exist but in very small quantities.
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Stars: Stars are composed of plasma, mostly hydrogen and helium, and they account for a significant fraction of baryonic matter. They are the primary sources of light and heat in the universe.
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Interstellar and Intergalactic Gas: Gas clouds, particularly those composed of hydrogen, fill the spaces between stars and galaxies. This matter can be found in various states, including ionized and neutral forms.
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Dust and Heavy Elements: While minimal compared to hydrogen and helium, heavier elements (like carbon, oxygen, and iron) formed in stars and distributed through processes such as supernova explosions also contribute to baryonic matter.
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Planets and Other Bodies: While much less common than stars and gas, planets, moons, asteroids, comets, and other celestial bodies also contain baryonic matter.
Overall, the universe is primarily made up of hydrogen and helium, with additional contributions from stars, gas, and various smaller bodies.