# Question about Finding Mass of Visual Binaries with Given Information

• pi-70679
In summary, you calculated the mass of Sirius A by assuming it was a main sequence star and estimating its radius from its mass.
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
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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Scooting this to Astronomy.

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
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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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.

## 1. What are visual binaries?

Visual binaries are a type of binary star system in which two stars can be seen orbiting each other from Earth without the aid of telescopes or other equipment. They are also known as "optical binaries" because they are detected through optical means.

## 2. How are visual binaries formed?

Visual binaries are formed when two stars are formed close enough together to be gravitationally bound to each other. As they evolve, their orbits become more circular and they can be seen orbiting each other.

## 3. What is the difference between visual binaries and other types of binary systems?

Visual binaries are different from other types of binary systems in that they can be seen directly from Earth without the use of telescopes or other equipment. Other types of binary systems, such as spectroscopic binaries, require specialized instruments to detect.

## 4. How are visual binaries studied?

Visual binaries are studied through direct observation using telescopes and other equipment. Astronomers can track the motion of the stars and measure their separation and orbital period to determine their properties, such as mass and distance from Earth.

## 5. What can we learn from studying visual binaries?

Studying visual binaries can provide valuable information about the properties and evolution of stars. By measuring the orbits of the stars, astronomers can determine their masses and understand how they interact with each other. This can also help us understand the formation and evolution of binary star systems as a whole.

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