Throwing water to the Sun

This summer’s intense heat has led me to wonder how one might turn off the sun. My initial thought was to douse it with water, like putting out a fire. After all, water extinguishes flames. Could we do the same with the sun? Perhaps by using a massive amount of water? say, ten times its own mass?

However, while water can extinguish a regular fire by absorbing its energy and disrupting the chemical reaction (oxidation), the sun’s energy production is fundamentally different. The sun operates through nuclear fusion, not combustion.

Common stars, usually form when gravity pulls together a hydrogen cloud. The more the cloud “collapses” the 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 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 gravitational 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 of 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 scenarios are possible, from spectacular supernova explosions, to black holes, to red dwarf.

So, what would happen if we dumped ten times the sun’s mass in water (hydrogen and oxygen) onto it?
Instead of cooling it down, we’d be adding fuel to the fire. The increased mass (11 solar masses) would significantly increase the gravitational pull, accelerating the fusion rate.
The new, more massive sun would be much hotter and brighter. Its diameter would 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!). Furthermore, the added mass would alter the star’s death, likely leading to a supernova explosion and potentially the formation of a quark star or even a black hole, rather than its expected quiet demise as a white dwarf.

Therefore, adding water to the sun would have the opposite of the intended effect. The only way to extinguish the sun with water would be to use an incredibly powerful water jet capable of completely dispersing its matter into space, preventing it from reforming under gravity.

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