Red+Giants+2B

What is bigger and cooler than the Sun? Red Giants, they are big balls of gas. Red Giants are relatively cool but very luminous because of its great size. All stars are expected to pass through a red-giant phase. As a star uses up its hydrogen by converting it to helium, its central core contracts while the outer layers expand and cool. This process produces the low temperature and larger size that characterize the red giant. Although most giant stars are red, some well-known giant stars are other colors near the red end of the spectrum. **Ex. Arcyurus (orange) ; Aldebaran (orange) and Capella (yellow).** The core of the star is hotter than it was during it normal life and this heat causes the outer parts of the star to swell. The star becomes a giant. The radiation from the fusing shell has grown weak by the time it reaches the surface of the star. Weak radiation is red, so the star becomes a **red giant**. = =