Properties of the Major Burning Stages of a 25 Solar Mass Star

Burning Stage

L_rad(Watts)

L_nu(Watts)

Temperature(K)

Radius(km)

Time (sec)

hydrogen==>helium

3.1x10³¹

....

39,800

4.2 million

2.3x10¹⁴

helium===>C,O

9.5x10³¹

7.3x10²⁷

15,800

47 million

2.1x10¹³

carbon===>Ne,Na

1.2x10³²

10³³

4,360

670 million

5.2x10⁹

neon===>O(??)

1.2x10³²

7.8x10³⁵

4,360

670 million

3.9x10⁷

oxygen===>Si,P,S

1.2x10³²

2.3x10³⁶

4,360

670 million

1.6x10⁷

silicon==>Fe-peak

1.2x10³²

3.8x10³⁸

4,360

670 million

1.2x10⁵

collapse

1.2x10³²

8.1x10⁴¹

4,360

670 million

0.35

The luminosity of the Sun is 4x10²⁶ Watts
The diameter of the Sun is 1.4 million km
One year is ~31 million sec
Note that after the onset of carbon burning, the Luminosity, Radius, and Temperature of the star do not change ===> we cannot tell (from visual observations) in what stage of nuclear burning the star sits. Carbon burning 170 years. The stages after carbon burning take around 1 year!