All stars of the Universe have in common that they are huge balls of gas that produce glow when burning their fuel, but not all are equally large or glow in the same way. Our Sun, for example, belongs to the G2 spectral class and is what is known as a yellow dwarf, a medium-sized star that has a life of 10.000 billion years.
The Sun: General characteristics
Even though our Sun is medium-sized compared to other stars in the Universe, it plays a central role in our solar system. The Sun spans the 99,86% of the mass of the solar system, making it the most massive object by far. This type star G2V It is brighter than 85% of the stars in the Milky Way, most of which are red dwarfs. Although the Sun appears to be a relatively stable star, it goes through different stages throughout its life, from its formation to its eventual death as a white dwarf.
G2 spectral class and the life cycle of the Sun
The Sun belongs to the spectral class G2, which means that its surface temperature is around 5,778 degrees Kelvin. Stars of this class are known as yellow dwarfs, and they have a considerably long lifespan. Our Sun, for example, has already reached half its life, at approximately 4.500 billion years since its formation.
Towards the end of his life, yellow dwarfs, like the Sun, are swelling, multiplying in size and becoming red giants. Experts believe that the Sun will expand to approximately the same area of the Solar System as the Earth.
Eventually, after exhausting its fuel, the Sun will contract again. In this phase, the gas it leaves behind will form a beautiful cloud around it known as a planetary nebulaOver time, and over billions of years, the Sun will stop shining brightly and become a white dwarf, eventually cooling down and becoming a black dwarf.
Evolution of stars and the future of the Sun
This phase of stellar death is common to many main sequence stars. Stars like the Sun, with similar masses, evolve in a predictable way. For example, the light emitted by the Sun is composed of 40% visible light and 50% infrared light.
The Sun, which has a mass of approximately 1.989 x 10^30 kilograms, will continue its nuclear fusion process by converting hydrogen into helium by other means 5,000 million yearsOnce the core runs out of hydrogen, helium will begin to fuse into carbon, marking the beginning of its transition into a red giant.
Internal structure of the Sun
The Sun is a huge sphere of plasma extremely hot. Inside it there are three main layers: the core, the radiative zone and the convection zone. The core is the hottest part, and is where nuclear fusion reactions that generate energy take place. The resulting energy is transported first through the radiative zone and then through the convection zone before finally reaching the photosphere, from where it is emitted into space in the form of visible light.
In addition to its internal structure, the Sun also has an atmosphere that includes the chromosphere and corona. During a total solar eclipse, the corona is visible as a bright white halo around the Sun.
The process of nuclear fusion: the engine of the Sun
The Sun's energy is produced through nuclear fusion, a process in which hydrogen nuclei combine to form helium, releasing a large amount of energy. This process is carried out under the principle of Einstein equation, E=mc², which transforms a very small amount of mass into a significant amount of energy.
The hydrogen fusion cycle in the Sun's core generates a huge amount of energy, which is eventually released as light and heat. This fusion also generates particles known as neutrinos, which travel through matter without being absorbed.
In the final stage of its life, when the Sun exhausts its hydrogen, it will begin to fuse helium in its core, leading it to expand and become a red giant. Eventually, after its transformation into a white dwarf, only a small remnant of its former glory will remain.
The importance of the Sun for life on Earth
The Sun is not only important to the Solar System in gravitational terms, but it is essential for life on Earth. Plants, in particular, depend on sunlight to carry out photosynthesis, a process that converts the Sun's energy into food for most life forms on Earth.
Furthermore, the heat generated by the Sun is what keeps Earth's temperatures within a habitable range. Without solar energy, the water cycle would not exist, and Earth would be an inhospitable planet for life as we know it.
El solar wind, composed of charged particles emitted by the Sun, plays an important role in the formation of phenomena such as the Northern Lights. In addition, the Sun is responsible for influencing space weather, which can disrupt telecommunications and satellite navigation systems on Earth.
Curiosities about the Sun
- The Sun takes 25 Earth days to complete one rotation at the equator, but at the poles the rotation period is extended to 36 days.
- The Sun emits light and heat, but in its atmosphere, known as the corona, temperatures reach more than 2.000.000 ºC, much higher than its surface.
- It takes light from the Sun approximately 8 minutes and 19 seconds to reach Earth.
Despite its incredible characteristics, the Sun is just one star among billions in the Milky Way. However, its importance for life on Earth is unquestionable, and its future as a red giant and white dwarf will be a spectacular cosmic event.