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| The Sun |
1. The luminosity is 4 x 1026 Watts. This is about 1019 dollars at current U.S. rates.
3. About 700 km.
5. One check is helioseismology. Because the propagation of sound inside the Sun is sensitive to the helium concentration, a detailed analysis of the long-wavelength vibrations of the Sun (which are more sensitive to the deep interior) provides a test. These data suggest that the interior helium concentration is indeed not very different from that of the surface.
7. Calculate, but it would take a very long time to lose much mass at that rate.