report on redgiants and typeII supernovae

Red Giant Stars Red Giants are very large, cool and luminous stars. This stage lasts about 10% of the stars life. They are old stars meaning they don't have much lifetime left. Red giant phase occurs in stars, which weigh less than 4 solar masses. The star starts to collapse towards the centre causing the star to heat up. The fusion rate increases within the outer shells; this causes the star to expand. The surface cools, making …

…endothermically decays to neutrons. The core collapses to 100km in a tenth of a second. Then in another second it becomes 10km. This causes a shockwave which can last up to 2 years. The shock reaches the star surface. Causing the temperature to rise to 200,000°c and explodes 15,000km/s. there is also a rapid raise in brightness. This process can occur in an order of seconds after a life time of a millions of years!