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Calculate combined apparent magnitude of two stars 
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#1
Sep2907, 04:50 PM

P: 569

1. The problem statement, all variables and given/known data
What is the combined apparent magnitude o a binary system consisting of two stars of apparent magnitudes 3.0 and 4.0 2. Relevant equations mn=2.5 log(f(m)/f(n)) 3. The attempt at a solution I know m= 3 and n=4 ,or vice versa. I'm not sure what this problem means by combined magnitude. Do they mean I should add m and n together? 


#2
Sep2907, 04:57 PM

HW Helper
P: 1,664

What you want to do is convert your magnitudes to intensities, since the intensities of the two stars can be added to give the total intensity (or brightness or power) of the pair. This leaves the question of what to use for a basis. You can pick any reference magnitude, say, zero, and compute the intensity of each star relative to the intensity of a zeromagnitude star. You would then add the intensities of each star and now compare the total intensity to that of the zeromag star to find the magnitude of the pair. 


#3
Sep2907, 05:05 PM

P: 569




#4
Sep2907, 05:11 PM

HW Helper
P: 1,664

Calculate combined apparent magnitude of two stars



#5
Sep2907, 05:13 PM

HW Helper
P: 1,664

Yes, that is what I'm describing. You should get intensities which are between zero and 1, since they are the intensities relative to a brighter star... 


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