- A red giant star is a dying star in the last stages of stellar evolution. In only a few billion years, our own sun will turn into a red giant star, expand and submerge the inner planets, possibly even Earth. Most of the stars in the universe are main sequence stars. Those converting hydrogen into helium through nuclear fusion. A main sequence star may have a mass between a third to eight times that of the sun and eventually burn through the hydrogen in its core.
- Red super giants are super giant stars of spectral type K-M and a luminosity class of I.They are the largest stars in the universe in terms of physical size, although they are not the most massive.Stars with more than about 10 solar masses, after burning their hydrogen become red super giants during their helium-burning phase.The radius of most red giants is between 200 and 800 times that of the sun, which is still enough to reach from the sun to Earth and beyond.
- Supernovas are vast explosions in which an entire star is destroyed. They are mostly seen in distant galaxies as 'new' stars appearing close to the galaxy of which they are members. They are extremely bright. For a few days, the combined light output of all the rest of the stars in the galaxy. As most observed supernova occur in very distant galaxies they are too blurry even for the largest telescopes to be able to study them and be able to see them clearly.
- Also, a red giant is a star that has exhausted the primary supply of hydrogen fuel at its core. An average-sized star like our Sun will spend the final 10 percent of its life as a red giant. In this phase, a star's surface temperature drops to between 3,140 and 6,741 degrees Fahrenheit and its diameter expands to 10 to 1,000 times that of the Sun. The star takes on a reddish color, which is what gives it its name.
- In the text,With no hydrogen left at the core of a star to fuel the nuclear reaction that keeps it burning, the core begins to contract. The core's contracting releases gravitational energy into the surrounding regions of the star, causing it to expand. Consequently, the outer layers cool down and the color of the star (which is a function of temperature) becomes red. The star may slowly shrink and expand more than once as it evolves into a red giant.