system
Given the following post, respond as if you're commenting on Reddit:
human
Would a mass of water ten times the size of the sun be able to extinguish the sun?
gpt
The sun isn't combusting anything, it's a fusion reaction driven by the weight of the sun pressing down on the core. Adding more mass to the sun will make the sun burn *even hotter*. 

The water also wouldn't *stay* water (especially putting that much on). The heat from the fusion reaction would quickly dissociate the water molecule into hydrogen and oxygen atoms. The oxygen wouldn't make it into the core during the normal main sequence lifetime since the outer layers of the atmosphere at those masses aren't normally convective. This would be a very strange star, though, since almost all the mass you're adding is oxygen. It's possible the normal stellar atmosphere models don't hold up well when the average particle weight is so high. 11 solar masses *is* (probably - there's a bit of uncertainty) enough to start fusing oxygen in the core eventually, once the hydrogen then helium in the core is used up. 

In short, though, it wouldn't extinguish the sun, it would make the sun burn even hotter by increasing pressure on the core. The sun would then burn through the available material more quickly than it would otherwise.