What is a Red Giant?
A red giant is a type of star. Its name is rather self-explanatory: it is red because of its relatively low temperature, and it is one of the largest of all star types, 1,000 times as voluminous as our Sun. Betelgeuse, Antares, Aldebaran, and Arcturus are some well-known red giant stars visible from Earth with the naked eye. A red giant is an aging star, and astrologists hypothesize that our Sun will become a red giant in about five billion years. Younger stars create energy through hydrogen fusion, which creates helium in the process, gradually causing the helium to hydrogen ratio inside the star to increase. Hydrogen is in the core of younger stars, but as a star ages and uses up its hydrogen store, the hydrogen becomes confined to an outer shell, while the core is only helium. In this scenario, the helium core has no fuel to burn, as helium fusion is possible only at very high temperatures, over 100 million Kelvin. Therefore, the helium core begins to contract, while the hydrogen sh
Briefly, it is a stage in the lifespan of a star. I was soon to find there was a lot more to this subject than I’d realised however… A star will spend the majority of its existance on the main sequence (an examination of the Hertzsprung-Russell diagram is highly recommended), during which it exists in a stable, very slowly changing condition, usually without any significant deviations in its temperature or brightness.. During this time, it converts hydrogen atoms into helium atoms by means of nuclear fusion. In the course of this transformation, there is an amount of excess mass, which is in turn changed into energy (determined by means of e=mc2). This emitted as visible light and other forms of radiated energy, commonly refered to as “sunshine”. Although this period of stability is measured in billions of years, nothing lasts forever… All very reasonable, but why does the star increase in size? The hydrogen, which forms the major part of a star is also its fuel source, and like al
