# How to use the Binary Mass Function for exoplanets?

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Hi. I am working on a research paper for my high school and I am trying to calculate the mass of an exoplanet using the radial velocity values of its star. However, I am confused as to the binary mass function and what units you would use. I also wanted to know how you would interpret a radial velocity curve to calculate the mass of the exoplanet. Thank you
The paper I am using for my radial velocity values is the following (Table 4)
https://iopscience.iop.org/article/10.1088/0004-637X/810/1/30
Hi. I am working on a research paper for my high school and I am trying to calculate the mass of KELT-8b using the radial velocity values of its star. However, I am confused as to the binary mass function and what units you would use. I was under the impression you would use solar masses however I am getting a mass of 3.48 solar masses which is nothing close to the mass they found in the paper. I also wanted to know how you would interpret a radial velocity curve to calculate the mass of the exoplanet because I figured maybe I found the radial velocity the wrong way. The way I did it was by taking an average of the peaks after graphing it against the time. Thank you
The paper I am using for my radial velocity values is the following (Table 4)
https://iopscience.iop.org/article/10.1088/0004-637X/810/1/30

Last edited:
Here is how to find how something is defined in a scientific paper.
1. Look for a definition in the paper.
2. If there is no definition, look for a reference to what you are looking for. Get that paper.
3. Look for a definition in that paper.
4. Repeat as needed.

Here is how to find how something is defined in a scientific paper.
1. Look for a definition in the paper.
2. If there is no definition, look for a reference to what you are looking for. Get that paper.
3. Look for a definition in that paper.
4. Repeat as needed.
Hi. I know how they have defined the radial velocity values. The problem is I do not know how the binary mass function works and what units you need for the function.

The phrase "binary mass function" does not appear in the paper you cite. Where did you come across the term and how is it defined?

Ibix said:
The phrase "binary mass function" does not appear in the paper you cite. Where did you come across the term and how is it defined?
Ok so, basically the paper I am writing needs me to calculate the mass using radial velocity method. After doing some research, I found the binary mass function in an Astrophysics textbook which I found could work for exoplanets. However the problem is that the units are not defined anywhere which is the main source of issue. As for how it is defined, the binary mass function constrains the mass of the unseen component of a binary system, which in my case is the mass. As for the paper I cited, I used it for the values of the radial velocity, however I am struggling a bit to understand how to condense them into one for my calculations. I ended up taking an average of the five highest values however I think my answer could have deviated due to the method I chose to condense the radial velocity values into one.

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