## Quick Reference

A mathematical relationship between the masses of the components in a spectroscopic binary and the orbital inclination. It is the only information about the masses that can be derived when the spectrum of just one star is visible. If that star is of mass *m*_{1} (in solar units), then the mass function is given by (*m*_{2} sin *i*)^{3}/(*m*_{1}+*m*_{2})^{3}, where *m*_{2} is the mass of the unseen star and *i* is the inclination of the orbit.

**From:**
mass function
in
A Dictionary of Astronomy »

*Subjects:*
Astronomy and Astrophysics.

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