Red+Giants+4B

="Red Giants"= The Herzsprung -Russell Diagram shows the relationship between the absolute magnitude and temperature of stars. Stars are classified by Specta, Temperature, and Luminosity. The Red Giant is above and to the right of the main sequence of stars in the HR Diagram.



The first stage of a star is its birth- the Nebula. Nebulae become dense enough to begin to contracts and gravity squeezes particles, which cause it to shrink. The second stage is the Protostar stage, a developing star that isn't hot enough yet to start nuclear fusion. When the core reaches approximatlely 10 million degrees Kelvin, a star is born. The main sequence stage is third. The vast majority of stars are in the Main Sequence. Hydrogen fusion continues for a few more billion years and gives the outward pressure to support the star from collapsing from gravity. The **Red Giant** is next, which is the second to last stage of a stars lifetime. The stars are much cooler than others, but are some of the brightest. As the Hydrogen fusion continuallly pushed outward, the red giant stage occurs. The Red Giants Temperature is usually between 2,500 and 3,000 degrees Kelvin. The core, which is mostly made up on Helium now, contracts. It grows hotter by converting gravitational energy into heat energy. When the star expands, it become cooler because of the vast size, which omits the red hue.The Red Giants emits weak radiation which results in the color red. As it expands, the core is heated to about 100 million degrees Kelvin. At this hot temperature the Helium can convert to Carbon. The Red Giant consumes both Hydrogen and Helium to produce energy. The final stage of a star is it's death. It is still unknown whether all stars burn out, reguardless of their size. Low mass stars become white dwarfs, where as massive stars like supergiants become black holes. Red Giants however, will either become a white dwarf or a neutron star.



Rigel is a well known Red Giant star and is the right foot of Orion. Rigel is the seventh brightest star in the sky.

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 * =Red Giants= For stars of less than 4 solar masses, hydrogen burn-up at the center triggers expansion to the red giant phase.