Power in Sun's Core: Comparing 10^26 W to 276 W/m^3

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SUMMARY

The discussion centers on the power output in the Sun's core, comparing it to a compost pile's power density of 276 W/m³. Participants calculate the core's power density to be approximately 17.5 W/m³ based on a fusion output of 3.86x10^26 W and a core radius of 173,950,000 m. The conversation highlights the misconception that fusion directly correlates with power density, emphasizing that the energy escape rate significantly influences the core's temperature and power generation. The discussion concludes that the Sun's luminosity remains stable even if fusion ceases, as gravitational contraction can sustain power output.

PREREQUISITES
  • Understanding of stellar physics and fusion processes
  • Familiarity with power density calculations
  • Knowledge of gravitational contraction in astrophysics
  • Basic principles of thermodynamics related to energy escape
NEXT STEPS
  • Research "Stellar Fusion Processes and Power Output" for deeper insights
  • Study "Gravitational Contraction and Stellar Evolution" to understand energy dynamics
  • Explore "Luminosity and Energy Escape in Stars" for advanced calculations
  • Investigate "Supernova Mechanisms and Stellar Collapse" for comparative analysis
USEFUL FOR

Astronomers, astrophysicists, and students of stellar dynamics will benefit from this discussion, particularly those interested in the mechanisms of energy generation in stars and the implications of fusion and gravitational processes.

  • #31
It appears I will not get an answer to my question, so for the benefit of the OPer, I will answer it myself: if you replace fusion in the Sun by a similar process that releases energy twice as fast at the same temperature and density, it will not have any significant impact on the luminosity of the Sun. This is obvious, is it not, from the well-known fact that the Sun's luminosity did not even change when fusion first initiated.
 
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  • #32
In one of Brian Cox's popular science broadcasts, he relates a history related to the sun's modest toaster oven power density. IIRC, he stated when the first estimates of the sun's radiated power were calculated (from the time to melt ice via sunlight on the Earth and the sun's distance was known), the results led some to the (seemingly wacky) guess that the sun was burning something like coal, as the total radiated power was a rough match for a coal fired body of that size. That coal would have been consumed too quickly did not immediately squash the hypothesis, since at the time a ~10,000 year old Sun/Earth was still fashionable.
 

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