K3L-Mass from Period and Separation

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Equation / Last modified by KurtHeckman on 2019/08/15 23:53
sspickle.K3L-Mass from Period and Separation

The Mass from Period and Separation calculator uses Kepler's 3rd law to compute the mass of a system (M) based on the distance (R) between astronomical bodies (e.g. a star and exoplanet) and the orbital period (T).

INSTRUCTIONS: Chose the preferred units and enter the following:

  • (R) This is the separation between the orbiting bodies.
  • (T) This is the period of the orbit.

Mass of the System: The calculator returns the mass of the orbital system (M) in multiples of the mass of the Sun.  However, this can be automatically converted to other mass units (e.g. kilograms or masses of the Earth or Jupiter) via the pull-down menu.

The Math / Science

In a binary system in which two objects orbit a common center of mass the mass of the system is related to the distance between the two objects (separation) and the period of their common orbit. This equation computes the mass of the entire system (both masses added together) given the two other quantities.

The formula for the Mass using Kepler's 3rd law is:

`M = (4 pi^2)/G  R^3/T^2`

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