# Visual binaries question

#### pi-70679

I have a question about visual binaries on a homework, which is at the link below.
http://pages.infinit.net/bdufou1/question2.jpg [Broken]
In addition to what is written in the question, we know that the sum of both masses is 3.3 times the mass of the sun, and Luminosity of A is three times that of the sun. I don't have any problem finding the radius of both stars, but i have no clue how to find the mass of each. I'm pretty sure the period is involved, but how??
Can somebody help??

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#### Tom Mattson

Staff Emeritus
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Scooting this to Astronomy.

#### marcus

Gold Member
Dearly Missed
Originally posted by pi-70679
I have a question about visual binaries on a homework, which is at the link below.
http://pages.infinit.net/bdufou1/question2.jpg [Broken]
In addition to what is written in the question, we know that the sum of both masses is 3.3 times the mass of the sun, and Luminosity of A is three times that of the sun. I don't have any problem finding the radius of both stars, but i have no clue how to find the mass of each. I'm pretty sure the period is involved, but how??
Can somebody help??
I looked at the page and it has a sketch of the paths
I measured with a millimeter measure on my computer screen
and saw that A was 5 mm above the CM line around 1965 about the same time that B was, it looked like 11 mm, or even 12 mm, below the CM line.

You have a situation where the less massive partner is swinging out 2.2 or 2.3 times farther from CM than the more massive partner goes.

If it's not obvious to you what the ratio of masses is, write back.

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#### pi-70679

Thanks a lot, but i found another way of doing it. I found out that sirius A is a main sequence star, and form a diagram of radius vs mass of main sequence stars i approximated the mass and i have the same answer as the theoretical one. So i guess it works. I thought about measuring the distance but it was really non-trivial since it was such a bad drawing. But thanks anyway, i guess i'll see if my way is right when i'll get my assignment back.

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