Understanding Our Sun & Its Different Zones Along With Fusion Reactions

Hello, Everyone!

The Sun is the center of our solar system and its gravitational pull keeps everything intact, i.e. all the planets, cosmic particles in its debris, moons, and asteroids in its orbits. Its association with our Earth brings different seasons, varying weather, and variating movements of seawaters and auroras-radiating light glowing in the sky in the nighttime due to ions emanating from the sun, and Earth's radiation blets-regions in the cosmos in which the energetic particles prevail entailing electrons and ions.

It is the nearest star to our Earth, but still very far away i.e. 93 MN. miles far from Earth. Life is possible on our Earth due to the Sun's heat. Lack of sunlight would have led to almost no life, food, or plants on Earth. Therefore it plays a pivotal role in making our Earth a beautiful place to exist.

But what is the Sun? What are the Sun's different sections or zones?

In this blog post, we will delve into understanding our Sun and the different solar zones.. So let's begin.

ABOUT SUN: Our Sun is a massive radiating sphere that entails hot plasma which is held by its gravitational pull. It is the star at the center of our solar system, and all the other planets orbit around it. The Sun's heat and light are cornerstones of the existence of life on Earth, its light provides the energy needed for photosynthesis in plants and regulation of climate by warming the air of Earth's atmosphere. The Sun majorly consists of hydrogen- about 74% and helium -about 24%.In the Sun's core nuclear fusion reactions take place and the energy emanated appears to us in the form of sunlight.

Here two questions arise. What is plasma and secondly what are the fusion reactions which occur at the sun's core?

Plasma is a fourth kind of matter that resembles gas but it has more diverse properties than gas. The plasma is a group of positive or negative ions -the particles that are deficient in electrons or have a surplus of electrons. The plasma is also referred to as Ionized gas because the charged ions have a characteristic of generating electricity. This phenomenal plasma is found in stars- our Sun, auroras-radiating light glowing in the sky in the nighttime due to ions emanating from the sun, and lightning.

Here two questions arise. What is plasma and secondly what are the fusion reactions which occur at the sun's core?

About Plasma:

Plasma is a fourth kind of matter that resembles gas but it has more diverse properties than gas. The plasma is a group of positive or negative ions -the particles that are deficient in electrons or have a surplus of electrons. The plasma is also referred to as Ionized gas because the charged ions have a characteristic of generating electricity. This phenomenal plasma is found in stars- our Sun, auroras--radiating light glowing in the sky in the nighttime due to ions emanating from the sun, and lightning-A type of plasma in which the electricity moving in air ionizes the regions in which it is moving. Henceforth a conductor path is created of charged air in such a way.

Now let us talk about fusion reactions.

Fusion Reaction: 2 light nuclei merge to create a heavy nucleus. The mass of the resulting nucleus is < mass of 2 light nuclei. The difference in the mass is released as energy.

A fusion reaction is the main source of energy for the sun which it radiates in the form of sunlight. Here in the fusion reaction, we mean a chain reaction of proton-proton {which are hydrogen nucleas} to get helium nuclei. Let us understand it:

-> 1. Formation of a deuterium nucleus:- Two protons of hydrogen {or we can say hydrogen nuclei} fuse to get the deuterium nucleas{1 proton +1 neutron}+ byproducts{positron-positively charged electron & neutrino-minute particle with no charge}

p+p→d+e++νe​

-> 2. Formation of Helium -3 nucleus: The resulting deuterium nucleus then collided with a {Hydrogen nucleas}-proton to get a Helium -3 nucleus {which has 2 protons and 1 neutron} & in this step, a gamma ray is also produced which is an electromagnetic radiation of very high energy. It is worth noting that for every collision between a deuterium with a hydrogen nucleus nucleus{proton}, a helium -3 is produced. Thus the number of Helium-3 nuclei = the number of collisions between deuterium with a proton.

d+ + p→3He+γ

-> 3. Formation of Helium-4 nucleus: In this step, two helium nuclei merge to form a helium -4 nucleus{2 protons+ 2 neutrons} + 2 free protons.

3He+3He→4He+2p

-> 4. A small amount of mass is converted into energy and energy is released: Interestingly, whi,e these ongoing steps a tiny amount of mass is transformed into energy based on Eeinstein's equation

E=Mc^2 { which means energy and mass are equivalent i.e. mass can be converted to energy and energy can be converted to mass}

There is a continuous chain of fusion reactions and there is not only one but immense chain reactions that occur in our Sun's core and hence the energy is released in the form of sunlight.=

Let us understand now about the solar zones.

ABOUT SOLAR ZONES:

Our sun has several layers or zones with every zone having different characteristics.

1. CORE: It is the innermost zone of the Sun where fusion reactions take place {helium is synthesized by fusion of hydrogen}; releasing massive energy that eventually appears to us as sunlight-the steps which we understood above.But, why only the core has nuclear fusion reactions? It is because of the core's intense temperature and pressure the hydrogen nuclei collide with one another {since the protons are positively charged and like charges repel each other there must be a force counteracting this repulsive force. This force comes from the high pressure in the sun's core which is extremely dense preventing these protons from repelling and making them collide with one another. we know that the greater the density higher the gravitational pull }. The high temperature renders the hydrogen protons enough energy to collide with one another and high pressure due to the intense gravity of the Sun makes Sun's core dense. Sun's core has temperature soaring to 15 million degrees Celsius or 27 million degrees Fahrenheit. The density of the core is 150 gms for every cubic centimeter.
   

2. RADIATIVE ZONE: This zone spans from the outer edge of the core to the interface layer which is the base of the convection zone. Here the energy released from the fusion reactions in the core is transported from one photon to the other { a photon is a particle of light to the other} as these photons bounce from photon to photon through the dense hot plasma in the radiative zone. This phenomenon is termed as radiation. But the time taken by the energy to travel by radiative zone is very large because of the bouncing of photons and dense material{hot plasma-ionized gas}. An individual photon might take millions of years to reach the tachocline/interface--> this region is based at the base of the Sun's convection zone. The density of the radiative zone follows a descending trend which implies that it decreases from the base of the radiative zone to the top of the radiative zone--the density is greatest near the core where the material{hot plasma/ionized gas} is denser as compared to the top {in the vicinity of interface layer }. The density of hot plasma in this zone is 20 gms per cubic centimeter but near the interface layer the density of hot plasma drops to 0.2 gms per cubic centimeter. A fall in temperature is also observed near the interface layer (2 million degrees Celsius) and the temperature is maximum at the bottom of the radiative zone near the core(7 million degrees Celcius).

3. INTERACTIVE LAYER/TACHOCLINE: It refers to the margin that demarcates the radiation zone and the convective zone. The area of this region is thinner when compared to the radiative and convective zones. However, it is a matter of fascination for scientists due to the discoveries. The top of this region is a bit calm owing to the slow motion of the hot gas. This layer plays a pivotal role in strengthening the magnetic field lines of the Sun as the various gases that flow through this layer stretch the magnetic lines making them potent eventually. There are changes in the chemical compositions of the material it is made up of and these changes leave behind the distinctive traits in the chemical compositions of the elements or components across the tachocline.

4. CONVECTION ZONE: It is the exterior layer of our sun spanning 2lac km beneath the surface which is visible to us. At the base of this zone, temperatures soar to 2 mn. degree celsius. The presence of heavy ions such as carbon, nitrogen, oxygen, calcium, and iron hold some of their electrons thus having a partial negative charge and they do not completely become cations by losing all of their electrons. This partial negative charge makes this zone opaque, because of the interaction of electrons with photons. Let us understand this. When light falls on these ions, it is either scattered or absorbed but it does not pass through the material. Therefore this zone is opaque. The heat is henceforth captured and the material begins to convect or boil.

Our sun has several layers or zones with every zone having different characteristics.

Pic Source:https://solarscience.msfc.nasa.gov/images/cutaway.jpg

Let us understand this convection process: The convection process occurs due to a fall in temperature with the rise in height. The hot material rises upwards, which is hotter than its encompassing areas; causing the heat to travel to the surface of the sun. The hot gas in the sun rises upwards because with height the pressure on the gas becomes lesser and lesser and the molecules in the gas start to drift away in a way that decreases their kinetic energy. Thus the temperature of the gas falls. {According to the kinetic theory of gases; the temperature of the gases is directly proportional to the average Kinetic Energy (energy of these moving molecules)of these gases. i.e. higher the temperature higher the Kinetic energy of the gases and vice-versa. } These rising gases create specific markings on the sun's surface referred to as granules and super granules {bigger patterns than granuels}.

When these gases come at the visible surface of the sun -called the photosphere their temperatures decrease and are 5,700 Kelvin but still enough high.

This is due to the following:

According to the kinetic theory of gases; gases are made up of molecules that are always in linear motion until they collide with one another or with the walls of the surface in which they are encased. If a collision happens then no energy is lost in the collision i.e. elastic collision happens. The temperature of the gases is directly proportional to the average Kinetic Energy (energy of these moving molecules)of these gases. i.e. higher the temperature higher the Kinetic energy of the gases and vice-versa. The pressure of the gases is due to the elastic collisions within these gases.

Conclusively, we can say that our sun is a glowing sphere of hot plasma and has different zones, every zone exhibits distinct characteristics.

Thank You.

REFERENCES:

https://www.space.com/17170-what-is-the-sun-made-of.html

https://science.nasa.gov/sun/

https://spaceplace.nasa.gov/all-about-the-sun/en/

https://education.nationalgeographic.org/resource/aurora/

https://www.energy.gov/science/doe-explainsnuclear-fusion-reactions#:~:text=Nuclear%20Fusion%20reactions%20power%20the,The%20leftover%20mass%20becomes%20energy.

https://solarscience.msfc.nasa.gov/images/cutaway.jpg