Throwing water to the Sun

This summer has been quite hot…So hot that I started to think how to turn off the sun for a while.. First thought would be to throw some water to the sun to cool it down. Will it work? After all, when you have a fire and you throw some water to it, it will cool down and eventually die off.. Can we do something similar with the Sun? Maybe throw a lot of water, like 10 time its mass to it?

Before we can answer we need to refresh a little chemistry first.. When a something catch fire here on earth is usually a oxidation reaction. In order to this reaction to ignite, it usually requires some sort of activation energy. Once that the reaction is ignited, it releases enough energy to self-sustain the reaction.  When we pour water on the fire, the water absorb part of the energy of the reaction (eg making it evaporate). If we use enough water, it will remove too much energy and the chemical reaction will be unable to self sustain: the fire will die off. So, will it works with the sun? Well, despite the sun looks like a fireball, is not quite the same. It works with nuclear fusion reaction.

Common stars, usually form when gravity pull together an hydrogen cloud. More the cloud “collapse” more the center of the new forming star will be crushed down from gravity pull.  This means that Hydrogen atoms in the center will be squeezed together. In the beginning they can resist to getting closer due to nucleus repulsion, however as the pressure and temperature increases, they will start to fuse together forming helium and the star ignites. At this point the gravitation force that tries to crash the atoms together, is balanced from the energy that is released by the nuclear fusion that push outwards and the star is in an equilibrium. This equilibrium can last millions to billions years and this is the period where the star is hot and stable. The nuclear fusion happening in the center of the star, generate (among the other things) neutrinos and photons (the light that we see). These photons can take up to millions of years before they reach the star surface and escape freely to space.
So, the nuclear reaction will continue fusing all the hydrogen into helium. Because Helium is denser than hydrogen, it will accumulate in the center of the star making the core itself also denser. If the star is massive enough, it can start to fuse also helium forming carbon. The process continue forming heavier elements such as lithium, oxygen and so on, all layered from the denser (in the core), to less dense (in the outer layers). All these fusion reaction will release energy, thus will make the star hotter and hotter. This process continue until the nuclear reactions fuses oxygen together forming Iron atoms that poison the star core, making the reaction stop. This happens because fusing iron atoms together is an endothermic reaction, meaning that it requires energy from the surrounding environment and thus will not happen in normal star conditions.. . So, when enough iron is accumulated in the star core, all the nuclear reactions stop. Without the external push from nuclear reaction, the gravity pull wins, crashing the star. Based on the size/mass of the star, different scenario are possible, from spectacular supernova explosions, to black holes, to red dwarf.

Now, back to our question. What happen when we throw 10 solar masses of water into the sun? Because water is formed by hydrogen and oxygen, it will look like that we will be throwing gasoline to a fire. Indeed the new sun with the much larger mass (11 solar masses), will have a much larger gravity pull (and a lot of fresh fuel!),  crashing the core much more and thus increasing the fusion reaction speed! The diameter of the new star will be only 5.8 times larger but the surface temperature will raise from 5800K to almost 20000K and the star luminosity will be increased by a factor of 1300!!!  Also, because now it is burning its “fuel” much quicker, the lifespan of the new sun is also reduced accordingly of a factor of close to 400 ( burn fast, die young! )!  By throwing such amount of water to the sun, you would also change how it will die. Indeed, sun  destiny is to die quietly, and after becoming a red giant for a period, it will became a white dwarf.  However, after that you added all those extra water, it will die with a nice supernovae explosion, probably forming a quark star and then a black hole.

So only throw water to the sun if you are cold and remember to wear good sunglasses before you do that (safety first)!

So the only way to switch off the sun with water is to use an insane powerful water jet capable of tearing sun apart and dispersing its atoms into the open space, so far away that will not be able to re-collapse by gravity pull.

Ps. I run all the calculation by myself. Please inform me if you found any mistake in it!



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