Does Higher Luminosity Mean Higher Power in Stars?

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Discussion Overview

The discussion centers on the relationship between luminosity and power in stars, exploring whether higher luminosity directly correlates with higher power output. It involves theoretical considerations and interpretations of stellar characteristics as represented in the Hertzsprung-Russell (H-R) diagram.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions if a star that is 10 times more luminous than another would indeed have 10 times more power, suggesting a direct relationship between luminosity and power.
  • Another participant confirms that luminosity, measured in energy per time (ergs/sec or joules/sec), is equivalent to power in watts, implying a direct correlation.
  • A layman participant notes that while white dwarfs have lower luminosity and absolute visual magnitude compared to main sequence stars, they can exhibit higher surface temperatures and other characteristics, raising the question of whether these factors relate to power.
  • A subsequent reply asserts that luminosity is indeed related to power, explaining that it represents the total power emitted by a star, and discusses the Stefan-Boltzmann law in relation to white dwarfs' high surface temperatures and low total luminosity due to their small radii.

Areas of Agreement / Disagreement

Participants express differing views on the implications of luminosity in relation to power, particularly in the context of white dwarfs versus main sequence stars. The discussion remains unresolved regarding the nuances of these relationships.

Contextual Notes

Some assumptions about the definitions of luminosity and power may not be fully articulated, and the discussion does not resolve the complexities of stellar characteristics as they relate to luminosity and power.

Mafia
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If one star is say 10 times more luminous than another star would that mean it would have 10 times more power as in W? And would that relationship continue with increased luminousity as in a star 1000 times more luminous would have 1000 times more power?
 
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Basically, yes. Luminosity has units of energy per time, and is typically measured in ergs/sec(CGS) or joules/sec(MKS), with joules per second being the same as watts.
 
As a layman, the way I read the H-R diagram, white dwarfs have less luminosity and less absolute visual magnitude than most main sequence stars, yet can have higher surface temperature, higher frequency color index (B-V), and higher surface current density. But perhaps this has nothing to do with power?

Respectfully submitted,
Steve
 
It does have to do with power. The luminosity is the power of the radiation that the stars emit. Since a star is roughly a blackbody, the total luminosity of a star is [tex]L =4\pi r^2 * \sigma T^4[/tex]
where sigma is the Stefan-Boltzmann constant. White dwarfs emit a lot of radiation per square cm of surface area because their temperature is high, but their total luminosity is low because their radius is so small.
 

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