Surface brightness to luminosity

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SUMMARY

The discussion focuses on the derivation of the surface brightness to solar luminosity conversion formula: S(mag/arcsec^2) = Mabs + 21.572 - 2.5log S (Solar luminosities/pc^2). The constant term 21.572 is questioned regarding its origin, whether it is an empirically observed value or derived from fundamental definitions. Participants clarify that the definitions of magnitude and parsec are arbitrary, suggesting that the constant can be understood through logarithmic manipulation of these definitions.

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  • Understanding of astronomical magnitude and its calculations
  • Familiarity with the concept of parsecs in distance measurement
  • Basic knowledge of logarithmic functions and their properties
  • Awareness of solar luminosity and its significance in astrophysics
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  • Research the derivation of astronomical magnitude and its implications
  • Study the relationship between parsecs and other distance units in astronomy
  • Explore logarithmic functions in the context of scientific calculations
  • Investigate the significance of solar luminosity in stellar classification
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Astronomers, astrophysics students, and anyone interested in understanding the conversion between surface brightness and solar luminosity in astronomical contexts.

Warimi
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Can anyone offer insight into the derivation of the surface brightness to solar luminosity conversion

S(mag/arcsec^2) = Mabs + 21.572 - 2.5log S (Solar luminosities/pc^2)

More or less my concern is the constant term, is it empirically observed value or is there a derivation for it?

thanks
 
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The definition of magnitude and parsec are arbitrary, and if you take the log of those (multiplicative) constants and add everything you should get 21.572 in some way.
 

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