Systems

Systems are sets of gravitationally bound non-stellar objects in orbit around one or multiple stars.

Properties
If a system has a planet for which the semi-major axis (i.e., in game terms, orbital radius) and orbital period are given, the star's standard gravitational parameter (Newton's gravitational constant multiplied by solar mass) may be derived from Kepler's Third Law. That is,

$$GM = \dfrac{4 \pi^2 a^3}{T^2}$$ Ascension of Ancients gives planetary orbital radius, a, in terms of AU, and orbital period, T, in terms of Earth years. From these, we can compute the mass of the star:

$$ M = \dfrac{4 \pi^2 a^3}{G T^2} = \dfrac {1.9899 \times 10^{30} \cdot a^3}{T^2} \; \mbox{kg} = \dfrac {a^3}{T^2} \; \mbox{Sol Masses} $$ (This according to Astronomy Today, 3rd Edition, pub. Prentice Hall Inc., 1998; pp 48-9.)

In order to obtain the highest possible precision for the stellar mass, the attributes of the system planet with the highest precision orbital radius and period should be used in the computation.