Cacus is a system with five worlds, four of which are terrestrial and one is a gas giant. While the system has some traffic due to being part of the Anansi-Ishtar shipping lane, its worlds have little in the way of resources and are mostly unexploited.

Its relative accessibility still allows it to function as a stand-in for truly remote places or as a jumping point to deep-space mysteries. Faringor is used as a movie location. Treyarmus is a stopover for freighters which the quarians often take advantage of to sell refreshments or trinkets. Chohe has some habitats made by solitary people or corporations researching its native life. Zayarter has mysterious lights that disappear on closer inspection.

Chohe

Chohe is the second planet orbiting the star Cacus.

Main article: Chohe

• Assignment: UNC: Besieged Base
• Collection: UNC: Asari Writings: Matriarch's Writings ×3
• Survey: UNC: Valuable Minerals: Heavy Metal ×1 / Rare Element ×1

Faringor

Faringor is the fourth planet orbiting the star Cacus.

Main article: Faringor

• Survey: UNC: Valuable Minerals: Rare Element ×1

Treyarmus

Treyarmus is the fifth planet orbiting the star Cacus.

Main article: Treyarmus

Xamarri

Xamarri is the third planet orbiting the star Cacus.

Main article: Xamarri

Zayarter

Zayarter is the first planet orbiting the star Cacus.

Main article: Zayarter

• Survey: UNC: Valuable Minerals: Heavy Metal ×1

Trivia

• The system is probably named for the 'centaur' Cacus and is probably a reference to Dante's Inferno, the first canticle of his Divine Comedy. In the Divine Comedy, Cacus is one of the guardians of the eighth circle of Hell.
• Keplerian ratios (a³/T²) may be derived for four of the orbiting planets. Of these, the outer planets Faringor and Treyarmus have the same ratio, which presumably corresponds with the solar mass. The inner planets Chohe and Zayarter diverge from this ratio and from each other.
• In Sol's system, Uranus and Neptune have similar discrepancies from Kepler's law, although not nearly as drastic. Their discrepancy is due to their mutual gravitational perturbation. Chohe and Zayarter – smaller planets – could be perturbed by an innermost "hot Jupiter" or protoplanetary matter not noted on this chart which make the solar mass seem locally greater than it is from Faringor's orbit.
• Airless worlds Faringor, Chohe and Xamarri at their distance are all too hot for a system with a main-sequence star of this mass; and Chohe's atmosphere is too tenuous for a planet that massive. It is likely that this star has not yet entered the main sequence. A proto-F0 would have more luminosity; and its planets would still be in the process of differentiation. Also, there is bismuth-208 in Faringor's core, which implies heavier elements and radioactivity in that planet and in those planets inside its orbit.