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## General InfoEdit

### WhatEdit

The mass function is applied to binary star systems and is useful for determining the lower limit for the companion star

$\frac {m _2 ^3}{(m_1 + m_2)^2} sin^3 i = \frac {P}{2 \pi G} v _{1r} ^3$

The right side of the above equation is known as the mass function

### Mass RatioEdit

We can compute a mass ratio of the two stars in the binary system by dividing the following quanties:

$\frac {m_2 ^3}{(m_1 + m_2)^2}sin^3i = \frac {P}{2\pi G} v _{1r} ^3$

$\frac {m_1 ^3}{(m_1 + m_2)^2}sin^3i = \frac {P}{2 \pi G} v _{2r} ^3$

We obtain:

$(\frac {m_2}{m_1})^3 = (\frac {v _{1r}}{v _{2r}})^3$

$\frac {m_2}{m_1} = \frac {v _{1r}}{v _{2r}}$