Find Apparent Magnitude of Binary Star System w/o Distance

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SUMMARY

The apparent magnitude of a binary star system can be determined using the known luminosities and absolute magnitudes of the individual stars, even when the distance to the system is not provided. The key formula utilized is the relationship between flux and apparent magnitude, expressed as F = L / (4πd²), where d cancels out for both stars in a binary system. The relative magnitudes can be calculated using the equation F₁/F₂ = 10^(0.4(m₂ - m₁)), allowing for the determination of apparent magnitudes based solely on the known values of the stars.

PREREQUISITES
  • Understanding of stellar luminosity and absolute magnitude
  • Familiarity with the concept of flux in astrophysics
  • Knowledge of binary star systems and their properties
  • Proficiency in mathematical manipulation of logarithmic equations
NEXT STEPS
  • Study the principles of stellar luminosity and its measurement
  • Learn about the calculation of apparent magnitudes in binary systems
  • Explore the use of flux in astrophysical calculations
  • Investigate the implications of distance in astronomical observations
USEFUL FOR

Astronomers, astrophysics students, and anyone interested in calculating the apparent magnitudes of binary star systems without distance measurements.

vivekdoulat
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Please could you let me know how to find out apparent magnitude of a star when you know the apparent magnitude of the binary star system?
p.s. the distance between the observer and the system is'nt given.

I have the luminosities of both the stars as well as absolute magnitudes of both the stars.
 
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Apparent magnitude of a star at a distance d depends on the flux F (of light) from the star through a unit area at that distance d. In other words, F=L/(4 pi d^2). Note that d appears in the equation. But it cancels if the distance of the two stars is the same (as in a binary) when computing the relative magnitudes.

Here's the formula for changing between fluxes and apparent magnitudes:
\frac{F_{1}}{F_{2}}=10^{0.4(m_{2}-m_{1})}
 
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