How does a star exist in space?

Because there is absolutely no fire in the sun. Fire is a chemical reaction, which does require oxygen. The sun (and other stars) is a thermonuclear reaction. In its core, hydrogen is fused to form helium. The fusion reaction generates an enormous amount of energy and requires no oxygen.

A fire can exist without oxygen, you need an oxidizing agent. The sun burns its hydrogen / heavier gases towards the end of its life The energy comes from the nuclear fusion within the sun.

I really kind of hate you. If you're a troll, then you're an infuriating troll, and if you're not a troll, then you're an idiot.

Fact: Space exists

Fact: The sun exists

Fact: The sun is in space

Fact: Fire can't burn without oxygen

Fact: There is no oxygen on/in the sun

Conclusion: Either our theory about what constitutes a fire is incomplete or the heat of the sun is generated by some other mechanism.

Fusion.

The Sun's energy does not come from chemical fire. Rather, it is generated in the Sun's core by the fusion of hydrogen nuclei into helium nuclei.

Also, the Sun is no more 'in space' than the Earth is. In fact, its atmosphere is far thicker than that of the Earth. Any oxygen the Sun contains, though, is not in its atmosphere but down in its core. The atmosphere is made of hydrogen.

Stars are not balls of "fire". Combustion is a chemical process and doesn't take place inside stars.

Stars produce their energy through nuclear fusion, which being a nuclear reaction has nothing to do with combustion and doesn't need any oxygen to take place.

The sun is a quagmire

It's not, made of fire

Forget what you've been told in the past

Nuclear fusion.

hydrogen burns by combining with other hydrogen, not oxygen... we call this type of fire "fusion".... hydrogen gas and fusion fire

Fire?

Try thermonuclear reactions, fire has nothing to do with it!