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

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Discussion Overview

The discussion revolves around the comparison of power output in the Sun's core, specifically contrasting the estimated power density of 276 W/m³ with a total power output of approximately 10²⁶ W. Participants explore the implications of these values, the nature of fusion processes, and the factors influencing energy generation in stellar environments.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions the validity of the 276 W/m³ figure when compared to the total power output of the Sun's core, suggesting a possible miscalculation.
  • Another participant emphasizes the importance of the solar core's size in determining power density and suggests that the power density is surprisingly low.
  • A participant notes that the power output is not constant throughout the core, with higher values expected at the center.
  • Some participants discuss the relationship between fusion processes and the time it takes for energy to escape the Sun, indicating that this affects the perceived power density.
  • One participant argues that the physics of fusion is more relevant to the power output than suggested, asserting that fusion generates energy that contributes to the 276 W/m³ figure.
  • Another participant introduces the concept of gravitational contraction as an alternative energy source, comparing it to fusion and discussing its implications for power output.
  • Concerns are raised about the implications of equating power density across different processes, questioning the validity of assuming uniformity in energy generation mechanisms.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between fusion processes and power density, with some arguing that fusion is not the sole factor influencing the 276 W/m³ figure, while others maintain that it is crucial. The discussion remains unresolved, with multiple competing perspectives on the nature of energy generation in the Sun's core.

Contextual Notes

Participants highlight the complexity of the relationship between fusion, gravitational contraction, and power density, indicating that assumptions about uniformity in energy generation processes may not hold true. The discussion also touches on the timescales involved in stellar processes, which complicate the understanding of power output dynamics.

  • #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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