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A massive star's core burns furiously fast. As it fuses larger
atoms together, it does so faster and faster, trying to maintain adequate
pressure on the inside to offset the gravitational pressure pushing in
from the outside. Below is the time scale over which a star 25 times the
mass of the sun, burns its internal fuel:
| Burning Stage | Surface T (K) | Radius | Seconds (Yrs) |
| Hydrogen | 40,000 | 6 Rsun | 2.3 x 1014 (7 Mill) |
| Helium | 16,000 | 70 Rsun | 2.1 x 1013 (500,000) |
| Carbon | 4,300 | 100 Rsun | 5.2 x 109 (100) |
| Neon | 4,300 | 100 Rsun | 3.9 x 107 (1 yr) |
| Oxygen | 4,300 | 100 Rsun | 1.6 x 107 (6 mos) |
| Silicon | 4,300 | 100 Rsun | 1.2 x 105 (1 day) |
| Iron | 4,300 | 100 Rsun | 0.35 seconds |
7 second = 1 year
When the core becomes solid Fe, there is no further energy production and the core immediately collapses within just a few seconds! The core collapse raises the temperature to several billion degrees. The Fe nuclei collide so violently they crush into neutrons. This releases an astronomical amount of energy from the core, which we see as a ..
Supernova!
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Supernovae are perhaps the most spectacular astronomical events to occur since the
original Big Bang! During a supernova, a single star will
have the light output of an entire galaxy full of Billions of
stars!
In February, 1987, a supernova went off in the Large Magellanic Cloud, called: Supernova 1987A. This was a tremendous opportunity for Astronomers (the last naked eye Supernova was in 1604). |