# Find Apparent Magnitude of Binary Star System w/o Distance

• vivekdoulat
In summary, to find the apparent magnitude of a star in a binary star system, you will need the luminosities and absolute magnitudes of both stars. The formula for converting between fluxes and apparent magnitudes is F1/F2 = 10^(0.4(m2-m1)). The distance from the observer to the system is not necessary for this calculation.
vivekdoulat
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.

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:
$$\frac{F_{1}}{F_{2}}=10^{0.4(m_{2}-m_{1})}$$

Last edited:

## 1. What is apparent magnitude?

Apparent magnitude is a measure of the brightness of a celestial object as seen from Earth. It is based on the object's intrinsic luminosity, distance from Earth, and the amount of light that reaches Earth.

## 2. How is apparent magnitude calculated?

Apparent magnitude is calculated using the formula m = -2.5 log(F), where m is the apparent magnitude and F is the flux or amount of light received from the object. The lower the apparent magnitude, the brighter the object appears to us.

## 3. Why is finding the apparent magnitude of a binary star system without distance challenging?

Finding the apparent magnitude of a binary star system without distance is challenging because the apparent magnitude of a binary system is dependent on the combined light of both stars. Without knowing the distance to the system, it is difficult to accurately determine the individual contributions from each star.

## 4. What methods can be used to determine the apparent magnitude of a binary star system without distance?

One method is to measure the total apparent magnitude of the system and then use spectroscopic techniques to determine the individual contributions from each star. Another method is to use photometric observations and modeling to estimate the individual magnitudes based on the observed total magnitude.

## 5. Why is it important to determine the apparent magnitude of a binary star system?

Determining the apparent magnitude of a binary star system allows us to understand the properties and behavior of the individual stars in the system. This information can provide insights into the evolution and dynamics of binary star systems, as well as contribute to our overall understanding of stellar evolution and the universe.

• Astronomy and Astrophysics
Replies
14
Views
1K
• Astronomy and Astrophysics
Replies
10
Views
4K
• Astronomy and Astrophysics
Replies
8
Views
2K
• Astronomy and Astrophysics
Replies
12
Views
1K
• Astronomy and Astrophysics
Replies
6
Views
2K
• Astronomy and Astrophysics
Replies
26
Views
2K
• Astronomy and Astrophysics
Replies
2
Views
868
• Astronomy and Astrophysics
Replies
6
Views
3K
• Astronomy and Astrophysics
Replies
49
Views
3K
• Astronomy and Astrophysics
Replies
10
Views
2K