The sun produces energy through a process called nuclear fusion, where hydrogen atoms combine to form helium. This process releases a tremendous amount of energy, which is what we perceive as the sun's heat and light. Unlike combustion, which requires oxygen, nuclear fusion does not depend on the presence of oxygen.
The term "burning" is often used colloquially to describe the sun's energy production. In reality, the sun is not actually burning like a fire on Earth. The process of nuclear fusion is very different from combustion and does not require oxygen.
Yes, other stars also produce energy through nuclear fusion and do not require oxygen to do so. In fact, the majority of stars in the universe are powered by nuclear fusion.
Oxygen is present on the sun, but it is not a significant factor in the sun's energy production. The sun's atmosphere does contain a small amount of oxygen, but it is not involved in the nuclear fusion process.
The sun has been burning for about 4.6 billion years and is expected to continue burning for another 5 billion years or so. However, it is important to note that the sun is not technically burning, but rather undergoing a process of nuclear fusion. Once the hydrogen fuel in its core is depleted, the sun will begin to expand and eventually become a red giant, marking the end of its "burning" phase.